Service trolley for electric vehicle batteries with configurable supports

Abstract

Service trolley (100), which includes: a frame (103) comprising a number of first strut members (105a; 105b), a number of second strut members (105c; 105d), a number of support members (107), a number of first cross members (109a; 109b; 109c) and a number of second cross members (109d; 109e; 109f), wherein all support members (107) are arranged between a first strut member (105a; 105b) and a second strut member (105c; 105d), all first cross members (109a; 109b; 109c) are arranged between respective ones of the number of first strut members (105a; 105b) and all second cross members (109d; 109e; 109f) are arranged between respective ones of the number of second strut members (105c; 105d); a first number of wheels (115), each of the wheels (115) being operatively coupled to at least one of the first strut members (105a; 105b) or one of the first cross members (109a; 109b; 109c); and a second plurality of wheel locks having a brake, each of the wheel locks being operatively coupled to one of the first plurality of wheels (115) and configured to apply a braking force to its respective wheel (115) when its brake is applied; wherein at least one of the second cross members (109d; 109e; 109f) is an adjustable cross member (111) configured for adjustably disposing between two of the second strut members (105c; 105d) in the longitudinal direction perpendicular to each of the second strut members (105c; 105d) with a predetermined degree of tolerance, and wherein each of the adjustable cross members (111) comprises a support pad (501) configured to provide a support force in a direction substantially parallel to the longitudinal orientation of the support members (107) with a predetermined degree of tolerance.

Description

TECHNICAL FIELDThe present disclosure relates to the repair and maintenance of electric vehicles and their associated batteries. More particularly, the present disclosure relates to tools useful in the repair and maintenance of electric vehicles and their associated batteries.BACKGROUNDElectric vehicles are becoming more and more popular with the improvement of their utility and reliability. Electric vehicles and their respective components still require maintenance for repair and maintenance work. Most electric vehicles have a large heavy battery suitable for powering the vehicle's propulsion source, which often must be removed from the vehicle's chassis to perform certain important maintenance operations on the vehicle or on the battery itself.Due to their size and weight, removing the batteries from their respective chassis is often difficult and time consuming and may require special tools in a specialized workshop environment. Such tools are often expensive, bulky and difficult to store.US 2013 / 0075993 A1 describes a cross member and carriage assembly for the transport and the assembly of cross member components. The cross bar includes a frame having a pair of parallel spaced side walls, couplings at the bottom sides thereof, and a vertical top wall. The frame has a pair of rails, with rails with slidable fasteners being attached to the inner surfaces of the side walls. The carriage has a base with rollers on a bottom and vertical supports extending from a top of the base and releasably receiving the couplings of the cross-member.DE 20 2013 000 849 U1 describes a rolling carriage, in particular a rolling container for fire weirs, having a chassis on four rollers. At least two rollers are steering rollers with a pivot bearing. Each wheel has a brake device, preferably a drum brake, which is permanently activated as a dead man brake by an engagement spring. The braking device can be released via an operating device on an operating frame and a movement transmission device.SUMMARYThe invention provides a service cart as recited in claim 1.One aspect of this invention is directed to a service cart suitable for the maintenance of electric vehicles and vehicle batteries. The service cart includes a frame including a number of first brace members, a number of second brace members, a number of support members, a number of first cross members, and a number of second cross members. All support members are disposed between a first strut member and a second strut member, all first cross members are disposed between respective ones of the number of first strut members, and all second cross members are disposed between respective ones of the number of second strut members. The service cart further includes a first number of wheels, each of the wheels operatively coupled to at least one of the first brace members or one of the first cross members, and a second number of wheel locks having a brake, each of the wheel locks operatively coupled to one of the first number of wheels and configured to apply a braking force to its respective wheel when its brake is applied. The service cart may be configured such that at least one of the second cross members is an adjustable cross member configured for adjustable placement between two of the second strut members longitudinally perpendicular to each of the second strut members with a predetermined degree of tolerance, and wherein each of the adjustable cross members includes a support pad configured to provide a support force in a direction substantially parallel to the longitudinal orientation of the support members with a predetermined degree of tolerance.Another aspect of this invention is directed to a service cart suitable for the maintenance of electric vehicles and vehicle batteries. The service cart includes a frame including a number of first brace members, a number of second brace members, a number of support members, a number of first cross members, and a number of second cross members. All support members are disposed between a first strut member and a second strut member. All the first cross members are disposed between respective ones of the plurality of first brace members. All the second cross members are disposed between respective ones of the plurality of second brace members. The service cart further includes a number of wheels, each of the wheels operatively coupled to at least one of the first brace members or one of the first cross members. The service cart further includes a number of wheel locks having a brake, each of the wheel locks operatively coupled to one of the number of wheels and configured to apply a braking force to its respective wheel when its brake is applied, the brakes of the wheel locks configured to be selectively engaged. In some embodiments, the service cart may further include a handle mount coupled to a first strut member or a first cross-member, and a handle having a push rod and configured to be releasably coupled to the handle mount, wherein brakes of the wheels are selectively engaged according to position of the push rod.Another aspect of this invention is directed to a service cart suitable for the maintenance of electric vehicles and vehicle batteries. The service cart includes a frame including a number of first brace members, a number of second brace members, a number of support members, a number of first cross members, and a number of second cross members. All support members are disposed between a first strut member and a second strut member, all first cross members are disposed between respective ones of the number of first strut members, and all second cross members are disposed between respective ones of the number of second strut members. The service cart further includes a number of wheels, each of the wheels operatively coupled to at least one of the first brace members or one of the first cross members. The service cart further includes a number of wheel locks having a brake, each of the wheel locks operatively coupled to one of the number of wheels and configured to apply a braking force to its respective wheel when its brake is applied. The service cart is configured such that the first cross members include a locking hinge and a number of the second cross members are second folding cross members including a locking hinge, the first cross members and the second folding cross members are each operable to adjust their respective coupling angles to their respective brace members when the locking hinge is released, and the frame may be arranged in a compact shape. The locking hinge may comprise a spring-loaded pin configuration.Yet another aspect of the invention is directed to a service cart suitable for the maintenance of electric vehicles and vehicle batteries. The service cart includes a frame including a number of first brace members, a number of second brace members, a number of support members, a number of first cross members, and a number of second cross members. The frame is configured such that all support members are disposed between a first strut member and a second strut member, all first cross members are disposed between respective ones of the number of first strut members, and all second cross members are disposed between respective ones of the number of second strut members. The service cart further includes a first number of wheels, each of the wheels operatively coupled to at least one of the first brace members or one of the first cross members, and a second number of wheel locks having a brake, each of the wheel locks operatively coupled to one of the first number of wheels and configured to apply a braking force to its respective wheel when its brake is applied. The frame is further configured such that at least one of the second cross members includes a support pad configured to provide a support force in a direction substantially parallel to the longitudinal orientation of the support members with a predetermined degree of tolerance, the support pad having a shank collar with a collar opening configured to receive a breakaway pin, the breakaway pin configured to be inserted into the collar opening and fracture when subjected to a shear force greater than a predetermined threshold.Another aspect of this invention is directed to a service cart suitable for the maintenance of electric vehicles and vehicle batteries. The service cart includes a frame including a number of first brace members, a number of second brace members, a number of support members, a number of first cross members, and a number of second cross members. The frame is configured such that all support members are disposed between a first strut member and a second strut member, all first cross members are disposed between respective ones of the number of first strut members, and all second cross members are disposed between respective ones of the number of second strut members. The service cart further includes a number of wheels, each of the wheels operatively coupled to at least one of the first brace members or one of the first cross members, and a number of wheel locks with a brake, each of the wheel locks operatively coupled to one of the number of wheels and configured to apply a braking force to its respective wheel when its brake is applied. The service cart may further include a tow hitch disposed on the frame, the tow hitch operable to releasably couple the frame to an external tow device. At least one of the tow hitch may include a pin hitch using a number of tow hitches and a tow hitch.The above aspects of this disclosure and other aspects will be explained in more detail below with reference to the appended drawings.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is an illustration of a service cart. FIG. 2 is an illustration of a frame of a service cart. FIG. 3 is a diagram of a frame of a service cart in a first arrangement. FIG. 4 is an illustration of a frame of a service cart in a second arrangement. FIG. 5 is an illustration of an adjustable cross member of a service cart. FIG. 6 is a schematic view of a support bracket and a sliding block in the support body of an adjustable cross member of a service cart. FIG. 7 is an illustration of a slide block for use in the inner portion of a support body of an adjustable cross member of a service cart. FIG. 8 is an exploded view of the components of a service cart support bracket. FIG. 9 is a cross-sectional view of a support pad configured to receive an external load. FIG. 10 is an illustration of a service cart with a braking system. FIG. 11A is a large-scale illustration of a service cart handle with a brake mechanism in a first position. FIG. 11B is a large-scale illustration of a service cart handle with a brake mechanism in a second position. FIG. 12 is a cross-sectional view of a wheel and associated brake for a service cart. FIG. 13 is a large-scale view of an adjusting pin and a brake housing for a wheel of a service car. FIG. 14 is a large-scale view of a service car wheel with a wheel fork and associated brake pad. FIG. 15 is a top view of a service cart illustrating the placement of a number of tow hitches compatible with an external tow device. FIG. 16A is a large-scale view of the hitch components of a service cart and the external tow device prior to hitching. FIG. 16B is a large-scale view of an external tow device releasably coupled to a service cart using their respective coupling components. FIG. 17A is a cross-sectional view of the hitch components of a service cart and the external tow device prior to hitching. FIG. 17B is a cross-sectional view of the coupling components of a service cart and an external tow device in the coupled state.DETAILED DESCRIPTIONThe illustrated embodiments are disclosed with reference to the drawings. It should be understood, however, that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of particular components. The specific details of structure and function disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art to practice the disclosed concepts.It should be understood that specific angular dimensions are provided by way of example and not limitation throughout this disclosure unless otherwise noted. The term "substantially perpendicular" is used herein to indicate a 90 degree angle within a specified tolerance required for the feasibility of the invention, as will be understood by one of ordinary skill in the art. The term "substantially parallel" is used herein to indicate a 0-degree angle within a specified tolerance required for the feasibility of the invention, as will be understood by one of ordinary skill in the art. It will be appreciated that all specific angular dimensions provided are, in practice, within a specified tolerance required for the feasibility of the invention, as will be understood by one of ordinary skill in the art.FIG. 1 shows a service cart 100 configured to support a battery 102. The battery 102 may include a battery for intended use with an electric vehicle. In the illustrated embodiment, the battery 102 may include a trapezoidal shape, however, the service cart 100 may be configured to receive and support batteries having various shapes and dimensions without departing from the teachings disclosed herein.The service cart 100 includes a frame 103 suitable for supporting the weight of the battery 102. The frame 103 is formed by a number of members coupled to provide a support base for the battery 102. The frame 103 may be composed of a number of stay members 105 arranged substantially parallel to the battery 102 and a number of support members 107 arranged substantially perpendicular to the battery 102. All of the brace members 105 may be coupled to one or more of the brace members 107 to form a brace substructure of the frame 103. In the illustrated embodiment, the strut sub-structures include couplings of strut members 105 and support members 107 at substantially perpendicular angles, however, other embodiments may include other arrangements without departing from the teachings disclosed herein. In the illustrated embodiment, the frame 103 includes two bracing sub-structures, however, other embodiments may include more bracing sub-structures without departing from the teachings disclosed herein.The frame 103 further comprises a number of cross members 109 interconnecting the sub-structures to form the overall structure of the frame 103. In the illustrated embodiment, the cross members 109 are coupled to the strut members 105 and the support members 107 in a manner that results in each cross member 109 being arranged at a substantially perpendicular angle to both the respective strut members 105 and the support members 107 to which it is coupled. In the illustrated embodiment, the frame 103 is composed of six cross members 109, however, other embodiments may include other configurations without departing from the teachings disclosed herein. The frame 103 may further include a number of adjustable cross members 111 that may be configured to accommodate various configurations of a battery. The adjustable cross members 111 may be detachable from the frame 103 without departing from the teachings disclosed herein. In the illustrated embodiment, the adjustable cross-members 111 are releasably coupled to the frame 103, however, other embodiments may include other configurations for some or all of the adjustable cross-members 111 without departing from the teachings disclosed herein.The service cart 100 may further include a handle 113 and a number of wheels 115 that allow a skilled technician to move the service cart 100. In the illustrated embodiment, the handle 113 may be coupled to one of the cross-members 109 and each wheel 115 may be coupled to the frame 103, but other embodiments may include other configurations without departing from the teachings disclosed herein.The service cart 100 may further include a number of tow couplings 117 configured to receive an external tow device, such as an electric tow device 119. The external tow device may be releasably coupled to the service cart 100 via one of the tow hitches 117 to assist a user in moving the service cart 100 under load. In the illustrated embodiment, each of the tow couplings 117 is coupled to the frame 103, but other embodiments may include other configurations without departing from the teachings disclosed herein. In the illustrated embodiment, the tow couplings 117 are configured to couple to an electric tow device 119, however, other embodiments may be configured to couple to other or additional types of external tow devices without departing from the teachings disclosed herein. The illustrated embodiment includes four tow couplings 117, however, other embodiments may include other configurations without departing from the teachings disclosed herein.FIG. 2 provides an additional view of the components of the frame 103. In this view, all of the strut members 105, support members 107, and cross members 109 have been identified as one of a row to see the orientation in Figure 2 and the following figures. In the illustrated embodiment, the brace members 105 aand 105 binclude a set of first brace members configured to be disposed closer to the ground than a charged battery (such as the battery 102, see FIG. 1 ) when the frame 103 is assembled and the service cart 100 (see FIG. 1 ) is charged. In the illustrated embodiment, the brace members 105 cand 105 dinclude a set of second brace members configured to be disposed closer to the battery than the ground when the frame 103 is assembled and the service cart 100 is loaded. In the illustrated embodiment, cross members 109 a, 109 b, and 109 ccomprise a set of first cross members configured to couple to each of the first brace members. In the illustrated embodiment, cross members 109 d, 109 e, and 109 fcomprise a set of second cross members configured for coupling between the second strut members. Other embodiments may include other sets of brace members 105, support members 107, and cross members 109 without departing from the teachings disclosed herein.The frame 103 may further include additional features that provide functionality to the service cart 100. In the illustrated embodiment, all cross members 109 may be coupled to other members of frame 103 via a number of hinges 209. The hinges 209 may be configured to allow range of motion for their respective cross-member 109 with respect to the attached brace member 105 or support member 107. In the illustrated embodiment, each of the hinges 209 is coupled to a strut member 105 on either side of the frame 103, however, other embodiments may include hinges coupled to support members or a combination of strut members and support members without departing from the teachings disclosed herein.The hinges 209 may advantageously allow the cross members 109 to be disposed relative to the brace members 105 and the support members 107 to achieve particular configurations of the frame 103. In the illustrated embodiment, the frame 103 is arranged as a rectangular prism, however, other embodiments may be configured differently to advantageously support various batteries having various shapes without departing from the teachings disclosed herein. In the illustrated embodiment, the hinges 209 may have a range of motion of 180 degrees to an associated brace member 105, but other embodiments may include other configurations without departing from the teachings disclosed herein.In some embodiments, the hinges 209 may include a flexible range of motion. In the illustrated embodiment, however, it may be advantageous that some or all of the hinges 209 include a hinge lock 211 operable to fix an associated hinge 209 in a particular angular arrangement. In the illustrated embodiment, the hinge locks 211 include spring-loaded pin locks configured to be received by the hinges 209, however, other embodiments may include other locking mechanisms without departing from the teachings disclosed herein. The hinge locks 211 may be operable to fix the arrangement of their respective associated hinges 209 at a range of predetermined angles, or may be configured to allow any angle without departing from the teachings disclosed herein. In the illustrated embodiment, hinges 209 associated with cross members 109 aand 109 dare provided by hinge locks 211, but other embodiments may include hinge locks 211 provided for any configuration of hinges 209 without departing from the teachings disclosed herein.The frame 103 further includes features useful for supporting other elements of the service cart 100 (see FIG. 1 ). In the illustrated embodiment, the frame 103 includes a number of handle couplings 213 operable for releasable coupling to a handle, such as the handle 113 (see FIG. 1 ). In the illustrated embodiment, hinge couplings 213 are coupled to cross members 109 aand 109 c, but other embodiments may include other configurations without departing from the teachings disclosed herein.The frame 103 may further include a number of wheel mounts 215 configured to provide a mounting position for wheels coupled to the frame 103 during full assembly of the service cart 100, such as wheels 115 (see FIG. 1 ). In the illustrated embodiment, the frame 103 includes wheel brackets 215 at intersections of strut members 105 and cross members 109 that form lowermost and outermost joints of the frame body. Other embodiments may include additional or alternative placements of wheel mounts 215 without departing from the teachings disclosed herein. By way of example and not limitation, the frame 103 may include a wheel mount 215 associated with each intersection of one of the first set of strut members 105 (e.g., the strut members 105 aand 105 b) and a support member 107.An additional advantage of implementing hinges 209 is that the frame 103 can be placed in a more compact or portable arrangement for stowage or transport. FIG. 3 illustrates a first arrangement of the frame 103 configured into a second more compact arrangement as shown in FIG. 4. In FIG. 3, the cross members 109 are arranged via their respective hinges (not shown, see FIG. 2 ) in a direction 300. Since all cross beams 109 are coupled to other links of the frame 103, the direction 300 is equally applied to all cross beams 109 in a matching manner. Other embodiments may have other configurations that result in non-matching array offsets without departing from the teachings disclosed herein. In the embodiment shown, the corresponding reconfiguration of the arrangement of the frame 103 can advantageously be carried out by a single technician.Fig. 4 is an illustration of the frame 103 after it has been arranged into a compact form. The compact shape of the frame 103 can be achieved because the cross beams 109 comprise folding cross beams which can be arranged at a desired minimum angle, and in the arrangement shown each of the cross beams 109 has been arranged at 0-degree angles to the strut members 105. It is noted that this arrangement is achieved by the joints associated with each cross member 109 via the hinges 209 (see FIG. 2 ). The hinges 209 may include locking hinges with hinge locks 211 (see FIG. 2 ) that, when placed in the compact assembly, may be used to restrict movement of the cross-members 109. FIG. 4 illustrates the frame 103 in the compact arrangement without other elements of the service cart 100 (see FIG. 1 ), however, the frame 103 may be configured into a desired arrangement while still being coupled to other elements of the service cart 100, such as the wheels 115 or the handle 113, without departing from the teachings disclosed herein. Advantageously, by configuring the arrangement of the frame 103 while still coupled to the wheels 115, a skilled person or other user can more easily move the frame 103 made more compact to a storage location.Referring again to FIG. 1, the service cart 100 includes a number of adjustable cross members 111 disposed between individual strut members 105 of the second set of strut members. In the illustrated embodiment, the adjustable cross-members 111 may be releasably coupled to the frame 103, but other embodiments may include other couplings, such as using a hinge, without departing from the teachings disclosed herein. In the illustrated embodiment, the adjustable cross-members 111 may be advantageously coupled to the frame 103 by a clamping mechanism, however, other embodiments may include other coupling mechanisms without departing from the teachings disclosed herein. In the illustrated embodiment, the clamping mechanism may include a screw lock to advantageously provide stability in the placement of the adjustable cross member 111 at a selected point in the length direction along its associated strut members 105.In the illustrated embodiment, the adjustable cross-beams 111 may be positioned at any point in the length direction along the strut members 105 between the cross-beams 109, however, other embodiments may include other configurations without departing from the teachings disclosed herein. In the illustrated embodiment, the adjustable cross beams 111 are positioned at a particular point along the strut members 105 by initial placement during assembly of the service cart 100, however other embodiments may include adjustable cross beams 111 that may be adjustably positioned without decoupling from the strut members 105. The placement of the adjustable cross beams 111 at particular points along the brace members 105 may advantageously allow the service cart 100 to support a variety of batteries having a variety of dimensions and characteristics. In some embodiments, the brace members 105 may additionally include indicia to provide an alignment aid for placement to a skilled technician to properly ensure that the adjustable cross members 111 are in a position suitable for receiving a particular battery shape relative to the brace members 105. In such embodiments, the markings may comprise a series of line markings that provide a ruler measurement system. Some configurations may include other marking systems suitable for incorporating specific battery designs, such as certain battery configurations from a particular manufacturer, or compatible with vehicles from a particular car manufacturer. Such embodiments may advantageously provide for a light configuration of the service cart 100 for a particular row of vehicles and may be more attractive to professionals working on those particular vehicles only.FIG. 5 is an illustration of features of an adjustable cross member 111. The adjustable cross member 111 is composed of a carrier body 500. To accommodate a variety of battery designs, adjustable cross member 111 also includes a number of support pads 501. The support shelves 501 are configured to be in direct contact with the battery when the service cart 100 (see FIG. 1 ) is loaded, and thus all support shelves 501 of the service cart 100, and thereby all adjustable cross beams 111, must be configured in combination to properly support the specific gravity of a battery. Each of the support shelves 501 includes a shelf facet 503 configured to be in direct contact with an outer surface of the battery when the service cart 100 is loaded. The support facet 503 may advantageously use a high coefficient of friction material to help maintain the battery in position when the service cart is loaded. In the illustrated embodiment, the liner facet 503 may comprise a polymer, such as silicone, but other embodiments may use any other material without departing from the teachings disclosed herein.The support support 501 further comprises a support shaft 505, which can advantageously be used for adjusting the vertical height of the support support 501 with respect to the carrier body 500. In the illustrated embodiment, the height adjustment of the support pad 501 may be achieved by rotating a shaft screw 507 coupled to one end of the pad shaft 505, however, other embodiments may include other configurations without departing from the teachings disclosed herein. In the illustrated embodiment, the shaft screw 507 may comprise a screw configured to engage a screw receiver inside the support shaft 505 (not shown). In the embodiment shown, the shaft screw 507 advantageously additionally secures the support shaft 505, so that the support shaft 505 cannot be removed from the carrier body 500 by mistake.Each support pad 501 is screwed through the support body 500 through a pair of shaft passages 509. All support pads 501 are threaded through their respective shaft channels 509 so that their respective pad shaft 505 can be placed at a position along the length of the support body 500. In the illustrated embodiment, each shaft channel 509 is configured to provide low friction in movement of a support shaft 505, but is also narrow enough, compared to the diameter of a support shaft 505, that a respective support pad 501 cannot freely rotate in a direction α. In the embodiment shown, the support shafts 505 are screwed through the complete height of the carrier body 500 and thus pass through two separate shaft channels 509 on opposite sides of the carrier body 500. Other embodiments may include other configurations without departing from the teachings disclosed herein.In the illustrated embodiment, each support shaft 505 is additionally threaded through a sliding block 511 disposed inside the support body 500. The seat shaft 505 may be threaded such that the associated slide block 511 is coupled to the seat shaft 505 upon bolting, such as a screw thread configuration. Each sliding block 511 may advantageously allow positioning of the support pad 501 in a length direction with respect to the support body 500.FIG. 6 provides an alternative side view of the support pad 501 and the sliding block 511 with respect to a support body 500 of the adjustable cross member 111. In the embodiment shown, a portion of the interior of the carrier body 500 can be seen within a section line 600. In the embodiment shown, the position of the support plate 501 is adjustable in two dimensions. The height settings of the support rest 501 control the position of the support rest 501 in a direction y in the manner described above with reference to FIG. 5. FIG. 6 additionally shows a direction x, which forms the longitudinal direction of the carrier body 500. In the illustrated embodiment, shaft channels 509 are configured such that support shaft 505 may move freely in direction x, although other embodiments may include other configurations without departing from the teachings disclosed herein. The slide block 511 helps to ensure that only linear positioning of the support pad 501 occurs by preventing rotational movement in a direction β.The sliding block 511 further includes a locking pin 613 disposed in a locking channel 615 of the support body 500. The locking channel 615 is separate from the shaft channels 509 because an edge is configured as a set of channel teeth 617. When the associated support pad 505 is subjected to a downward load on the pad facet 503 (such as when supporting a battery), the locking pin 613 may be pressed between two adjacent channel teeth 617. When the locking pin 613 is pressed between adjacent channel teeth 617, the slide block 511 may not be operable to move in the direction x, and the support pad 501 may be advantageously fixed in a position under load. To ensure that the support pad is freely positionable when not under load, the sliding block 511 may include a sliding spring 619 operable to provide an upward force in the direction y when not under load. Because the support pad 501 and the slide block 511 are effectively coupled when the pad shaft 505 is threaded through the slide block 511, by applying pressure from the battery to the surface facet 503, a force opposite the upward direction is provided by the slide spring 619. In the illustrated embodiment, the associated battery may be very heavy, however, the slider spring 619 need not provide sufficient force to support a significant portion of the battery weight to be effective, and instead need only provide sufficient force to counteract the combined weight force of the support pad 501 and the slider block 511 when coupled, but not under load. In the illustrated embodiment, the sliding spring 619 may be operable to provide a sufficiently low upward force so that a skilled worker can easily manually manipulate the sliding block 511 upon inspection of its operation. By way of example and not limitation, the illustrated embodiment may include a slider 619 that can produce 10 pounds force, but other embodiments may include other specifications without departing from the teachings known to one of ordinary skill in the art. However, it should be appreciated that preferred embodiments of sliding springs 619 do not provide sufficient force in combination with all sliding springs of the associated embodiment to fully support the weight of a battery that loads service cart 100 (see FIG. 1 ). In the illustrated embodiment, the locking pin 613 may be advantageously configured to resist much greater shear forces than an associated sliding spring 619, as the locking pin 613 is exposed to a greater weight from the battery when the service cart is loaded. By way of example and not limitation, the locking pin 613 in the illustrated embodiment may be capable of withstanding a shear force of 1000 Ib under load, but other embodiments include other configurations that are capable of their associated expected loads without departing from the teachings disclosed herein.The support body 500 may further include markings or dimensions thereon to provide a measurable indication of the position of a support surface 501 to users and skilled artisans. In some embodiments, the channel teeth 617 may be numbered or marked with pitch measures to provide a position indicator (not shown). In other embodiments, some or all of the channel teeth 617 may include special colors that indicate particular positions for the support pads 501 relative to a particular type of battery to be supported (not shown). Other labels may be used in other embodiments without departing from the teachings disclosed herein.FIG. 7 is a diagram of the sliding block 511 independently of its arrangement with respect to a carrier body 500 (see FIGS. 5 and 6 ) of an adjustable cross member 111. The slide block 511 is composed of a lock pin 613 and a slide spring 619. In some embodiments, the sliding block 511 may include additional or differently configured locking pins 613 without departing from the teachings disclosed herein. In embodiments with multiple locking pins 613 on opposite sides of the sliding block 511, the support body 500 of the adjustable cross member 111 may include multiple locking channels 615 (see FIG. 6 ) for receiving the sliding block 511. In configurations with multiple locking pins 613, the shear resistivity of the locking pins 613 as a whole can withstand the specific gravity under load. By way of example and not limitation, a sliding block 511 with 4 locking pins 613 may still be operable to resist a shear force of 1000 Ib, but each individual locking pin 613 may be configured to resist a shear force of 250 Ib alone (1 / 4 of the total maximum load). Such embodiments may advantageously reduce the cost of the sliding block 511 by using less expensive materials for the locking pins 613. Other embodiments may include other configurations without departing from the teachings disclosed herein.FIG. 7 also illustrates a shank receiver 701 operable to receive and screw a support shank 505 (see FIG. 5 ). In the illustrated embodiment, the shaft receiver 701 may include an interior having a screw thread that mates with a screw thread of an associated support shaft 505, but other embodiments may include other configurations without departing from the teachings disclosed herein.The sliding block 511 may further include a sliding shoe 703 configured to be inserted into an inner slot (not shown) in the support body 500 (see FIGS. 5 and 6 ). The slide shoe 703 can be engaged with the inner slot with a low coefficient of friction to allow unimpeded movement of the slide block 511 in the carrier body 500 under no load. However, the use of the shoe 703 in an internal slot may advantageously prevent the shoe 511 from rotating or otherwise displacing in the carrier body 500 such that a support shaft 505 may not be successfully threaded through the shaft receiver 701 during assembly, repair, or reassembly of the adjustable cross-member 111. Some embodiments may not include a shoe 703 or inner slot of the support body 500 without departing from the teachings disclosed herein.FIG. 8 includes an exploded view of a support pad 501. In the illustrated embodiment, the shaft screw 507 is coupled to the support facet 503 via a shaft collar 801 configured to receive the support shaft 505. The support seat 501 is additionally composed of a number of collar holes 805 forming a through hole in the shaft collar 801 and a number of shaft holes 807 forming a through hole in the seat shaft 505. When the support shaft 505 is received in the shaft collar 801, the collar openings 805 and the shaft openings 807 may be aligned such that a break-off pin 809 may be inserted into the through hole formed by its alignment.Vehicle batteries are usually very heavy and are arranged along the chassis of their associated vehicles. By way of example and not limitation, a battery suitable for a typical electric vehicle may weigh between 1000-3000 lbs, and the battery of a light duty electric truck may weigh 5000 lbs or more. In the embodiments illustrated herein, the service cart 100 (see FIG. 1 ) may be configured to securely accommodate batteries having loads greater than 5000 Ib. Due to the weight and arrangement of batteries with respect to their electric vehicles, a conventional approach to loading the service cart 100 may include using an additional high-power jack (such as an electric, pneumatic, hydraulic, or hybrid jack found in conventional motor vehicle workshops) to raise the entire vehicle to a height high enough that the service cart 100 may be placed underneath, and then slowly lowering the vehicle onto the service cart 100 until the battery comes into contact with the support pads 501 (see FIG. 5 ) before decoupling the battery from the associated electric vehicle. In such a procedure, the assembly of service cart 100 is ideally properly configured for the battery it is to accommodate.The breakaway pin 809 may be constructed as a disposable component that is sacrificed when the support pad 501 is subjected to a higher weight during the loading procedure than according to its design. This sacrifice of the break pin 809 may advantageously provide an audible, visual, or haptic feedback indication of one or more support pads 501 having been subjected to an excessive load, and the skilled artisans may use such feedback to continue using the high-power jack to support the weight of the vehicle and / or the battery. Such feedback may advantageously protect workers from unsafe loading of service cart 100, and prevent other components of service cart 100 from requiring repairs or replacement, the service cart would be exposed to loads that may cause damage.In the illustrated embodiment, the break pin 809 may be subjected to shear forces from the shank collar 801 when loaded with a battery. Each of the support shelves 501 of the service cart 100 may be expected to be subjected to a partial load of the overall weight of the battery. Thus, the break pin 809 may advantageously be configured to break when subjected to a load exceeding its associated specific capacity. By way of example and not limitation, the break pin 809 in the illustrated embodiment may be configured to withstand a shearing force of 1250 lbs to accommodate a maximum battery weight of 5000 lbs distributed across four individual support pads 501 (see FIGS. 1 and 5 ). In other embodiments, the break-away pins 809 may be configured to accommodate smaller 1000 Ib batteries and thus may be configured to withstand only 250 Ib shear forces. In some embodiments, the break-away pins 809 may be configured to break at a lower weight when it is assumed that the battery's own weight will not be evenly distributed on the service cart 100. By way of example and not limitation, if a battery weighs 1000 lbs but 70% of its weight is distributed on one side of its casing, half of the break pin 809 may be configured to have a higher break point (e.g., 350 lbs shear force) and the other half may be configured to have a lower break point (e.g., 150 lbs) so that professionals may be informed in a manner that optimizes safety if the load of the battery is not evenly distributed on the service cart 100.In the illustrated embodiment, breaking a break pin 809 may generate a loud audible sound when the break pin 809 breaks. In some embodiments, a surface 811 of the support shaft 505 may include an open electrical circuit (not shown) that is closed by contact with an inner surface in the shaft collar 801. The closed electrical circuit may be used to energize a visual indicator such as an LED or an audible indicator such as a buzzer or siren. In some such embodiments, the collision of surface 811 with an inner surface itself may produce a loud and clearly audible sound that indicates to a skilled artisan that an associated break pin 809 has been sacrificed.FIG. 9 is a cross-sectional view of an assembled support pad 501 when configured to be subjected to a load. In the embodiment shown, the support shaft 505 is accommodated in a void 901 in the shaft collar 801. The break pin 809 is inserted into a through hole formed by aligning the openings of the support shaft 505 and the shaft collar 801. The break pin 809 can be used to maintain some amount of clearance between the surface 811 of the support shaft 505 and within the void 901. If the break pin 809 breaks due to application of an excessive shear force to one or both ends through the shaft collar 801, the downward force 913 of the external load presses the shaft collar 801 downward onto the support shaft 505, causing a collision and contact between the surface 811 and the surface 911.The service cart 100 may include other features that are directed to safety and ease of use for those skilled in the art. FIG. 10 is an illustration of a service cart 100 having a brake system integrated with the handle 113. The handle 113 may be coupled to the service cart 100 via a handle bracket 1013. In the illustrated embodiment, the service cart 100 includes a plurality of handle mounts 1013 attached to both sides of the cart frame 103 (see FIG. 1 ), however, other embodiments may include a different number of handle mounts 1013 without departing from the teachings disclosed herein. In the illustrated embodiment, the handle 113 may be releasably coupled to the service cart 100 so that it may be secured on either side of the cart, but other embodiments may include a different coupling mechanism without departing from the teachings disclosed herein. In the illustrated embodiment of FIG. 10, the service cart 100 may include an optional second handle 114 such that both the handle 113 and the handle 114 may be simultaneously coupled to the service cart 100 using different handle mounts 1013. Advantageously, by having a plurality of handle mounts 1013 and coupling a plurality of handles to the service cart 100, easy access to the cart can be provided for a plurality of skilled personnel, thereby facilitating the effort for each skilled personnel to securely move the cart when loaded. In the illustrated embodiment and throughout the specification, unless otherwise noted, the handle 114 is identical in shape and function to the handle 113, but other embodiments may include a plurality of handles having various configurations without departing from the teachings disclosed herein. Unless otherwise noted, descriptions of the handle 113 in this disclosure also apply to the handle 114 in embodiments that include a second handle 114.In the illustrated embodiment, the service cart 100 includes a brake system composed of brake cables 1015 configured to cooperate with the handle 113 via the handle mounts 1013. Each of the wheels 115 includes an associated brake housing 1017 in which a brake engagement mechanism (not shown) is located. The engagement mechanism of each brake housing 1017 may be engaged via one of the brake cables 1015. In the illustrated embodiment, selective engagement of the brake cables 1015 is achieved via control within the handle 113. In the illustrated embodiment, the brakes of the wheels 115 are normally engaged and the control in the handle 113 may include a push rod 1019 operable to selectively disengage the brakes (sometimes referred to as a "dead man control"). Other embodiments may include other configurations, however, the illustrated embodiment may advantageously use a normally engaged brake to maximize the stability of the cart when loaded without relying on a skilled worker to separately engage the brakes, thereby improving the safety for the cart and the skilled worker. The push rod 1019 can provide ergonomic control of the brakes so that a skilled person, when positioned on the handle 113, can easily disengage all brakes simultaneously, thereby advantageously maximizing comfortable operation of the cart even when loaded.In the illustrated embodiment, the handle 113 may be releasably coupled to the cart via the handle mounts 1013, and thus the handle mounts 1013 provide a channel for coupling the push rod 1019 into the handle 113 to the brake cables 1015. Other embodiments may include other mechanisms for such coupling without departing from the teachings disclosed herein. In embodiments with both handles 113 and 114, each handle may include a push rod 1019 operable to selectively disengage the brakes. In some embodiments with both handles, such as cars, designed to support very heavy loads, both handles may have to be selectively actuated to disengage the brakes of the wheels 115, thus advantageously inducing two professionals to be present when moving the car under load, thus improving safety.In the illustrated embodiment, the push rod 1019 of a single handle 113 may be operable to control brakes associated with each of the wheels 115. For this purpose, a number of cable switches 1021 are fastened to the frame of the service cart 100. Each switch 1021 is configured to connect a single brake input cable 1015 coupled to the handle 113 to a plurality of brake output cables 1015 that directly apply the brakes of the wheels 115. The illustrated embodiment includes a pair of switch gates 1021 located on either side of the handle mounts 1013, thereby providing for a linked handle 113 access to the brake mechanisms of all brakes on the side of the service cart 100 with respect to the handle 113. In such an embodiment, this configuration allows each brake associated with a wheel 115 of the service cart 100 to be disengaged from a single handle 113 using a single controller, such as the push rod 1019. In this configuration, the push rod 1019 is operable to disengage all brakes when its associated handle 113 is attached to the service cart 100 and the brake cables 1015 are coupled thereto via the handle mounts 1013. Other embodiments may include another arrangement with a different number or configuration of cable diverters 1021 without departing from the teachings disclosed herein.The illustrated embodiment includes a normally engaged brake configuration that is accessed via push rod 1019. Such a configuration may be awkward for a single technician who must move the service cart 100. FIG. 11 includes a large view of a feature of the handle 113 that may be used to assist a single professional in the actuation of the brakes.FIG. 11A provides a view of the handle 113 when the push rod 1019 is not actuated (and thus the brakes of the carriage are engaged). In the illustrated arrangement, the push rod 1019 is inserted into a rod channel 1100 that allows the push rod 1019 to move along a predefined path for optimal disengagement of the brakes (not shown). By applying an upward force 1112 to the push rod 1019, the push rod 1019 may be positioned in an actuated position (thereby disengaging the brakes). The handle 113 further includes a latch 1113 operable to be positioned to hold the push rod 1019 in the actuated position without continued application of the force 1112. The latch 1113 includes a sleeve latch operable to slide along the length of a handle member 1115. The latch 1113 is further operable to rotate about the exterior of the handle member 1115. The combined movements of the latch 1113 may be used to move the latch 1113 in a direction 1116 to a position between the push rod 1019 when in an actuated position and a latch latch lock 1117 that is in a downward direction from the push rod 1019, as shown in FIG. 11B. In FIG. 11B, the latch lock 1117 provides a stabilizing force 1118 to counteract a downward force 1120 to which the push rod 1019 is exposed in attempting to return to its normally disengaged state. Although the illustrated embodiment includes a slide latch and a cylindrical handle member, other embodiments may include other latch mechanism configurations without departing from the teachings disclosed herein. Some embodiments may not include a latch mechanism for any handles 113 of a service cart without departing from the teachings disclosed herein.FIG. 12 illustrates a cross-sectional view of a wheel 115 mounted to a service cart via a wheel mount 215 (see FIG. 2 ) and having a brake housing 1017 actuated via a brake cable 1015 inserted through an entrance into the brake housing. The brake cable 1015 is operated by supplying a force 1200 to a brake push rod 1201. The brake push rod 1201 is coupled to the brake cable 1015 and is supplied with a normal force 1200 running in the opposite direction via a compression spring 1203. The forces are transferred from the brake push rod 1201 to a shoulder pin 1207 and a brake pad 1209, where the brake pad 1209 is coupled to the brake push rod 1201 using the shoulder pin 1207. When the force 1200 is not present, the compression spring 1203 supplies a normal force that causes the brake pad 1209 to contact the wheel 115. Thus, application of a force 1200 via brake cable 1015 is required to disengage brake pad 1209 and allow unimpeded movement of wheel 115. In the illustrated embodiment, wheel 115 includes a caster that can pivot about an axis parallel to brake push rod 1201, but other embodiments may include other configurations without departing from the teachings disclosed herein. By way of example and not limitation, wheel 115 may have a 360 degree pivot motion about this axis, but other embodiments may include other configurations without departing from the teachings disclosed herein. In the illustrated embodiment, the brake pad 1209 is operable to provide braking force to the wheels at a level sufficient to stabilize a service cart 100 (see FIG. 1 ) in combination with other similar brakes for the wheels available when loaded. By way of example and not limitation, the illustrated embodiment may be operable to provide a braking force of 250 lbs. Other embodiments may include other braking forces suitable for other service cart configurations or other configurations of batteries that load the service cart without departing from the teachings disclosed herein.FIG. 12 also illustrates an adjustment pin 1211 coupled to the brake push rod 1201 that is operable to stabilize the position of the brake pad 1209 as part of a pin-slot system. FIG. 13 provides a large view of the operation of the pin-slot system including the adjustment pin 1211 with respect to the brake housing 1017. The adjustment pin 1211 is configured to move in a pin channel 1300 of the brake housing 1017. The pin channel 1300 includes a channel branch 1302 having a proximal end 1304 and a distal end 1306. When a force 1200 is applied to the brake cable 1015, the adjustment pin 1211 moves along the pin channel 1300 in the direction 1308 and ultimately passes through the proximal end 1304 and toward the distal end 1306. When the force 1200 is released, the adjustment pin 1211 is pressed by the compression spring 1203 (see FIG. 12 ) in the opposite direction 1308 into its initial position. The width of the pin channel 1300 and channel branch 1302 is calibrated to provide sufficient space for unobstructed movement of the adjustment pin 1211, but only within a fixed tolerance in a direction other than the direction 1308 or the direction of reverse thereto. The calibrated width of the channel 1300 and the channel branch 1302 advantageously stabilizes the movement of the adjustment pin 1211, thereby providing for smooth movement during application of the force 1200 and during return of the adjustment pin 1211 to its initial position. Moreover, the fixed width of the channel branch 1302 helps stabilize the movement of the adjustment pin 1211 as it passes through the proximal end 1304 as it is displaced, thereby allowing small variations in the force 1200 without resulting in re-application of the brake pad 1209 (see FIG. 12 ) to the wheel 115. In the illustrated embodiment, the channel 1300 includes an oblique L-shaped channel having the channel branch 1302, however, other embodiments may include other configurations of the channel 1300 and the channel branch 1302 without departing from the teachings disclosed herein. Some embodiments may not include the adjustment pin 1211 and / or the channel 1300 and / or the channel branch 1302 without departing from the teachings disclosed herein.As mentioned above with reference to FIG. 12, the wheel 115 may pivot about an axis parallel to the brake push rod 1201. Because the brake pad 1209 is more efficient when a greater portion of its surface area contacts the wheel 115, it would be advantageous for the brake pad 1209 to pivot together with the wheel 115. Thus, the brake pad 1209 may be configured to pivot about the same axis with the same degree of freedom as the wheel 115. In the illustrated embodiment, the brake pad 1209 may include a 360 degree degree degree of freedom for pivoting about this axis, but other embodiments may include other configurations without departing from the teachings disclosed herein. FIG. 14 provides a view of an embodiment of the wheel 115 with a number of wheel forks 1401. In the illustrated embodiment, the wheel forks 1401 are configured for coupling to the wheel 115 via a bolt at its axis of rotation, however, other embodiments may include other configurations without departing from the teachings disclosed herein. The wheel forks 1401 are arranged to provide a smooth rotational force to the brake pad 1209 about its pivot axis whenever the wheel 115 pivots about the same axis. By way of example and not limitation, in the illustrated embodiment, the wheel forks 1401 are configured to cause the brake pad 1209 to pivot in a rotational direction 1402 whenever the wheel 115 pivots in the rotational direction 1404. It is noted that the rotational directions 1402 and 1404 are parallel about the same rotational axis, and thus the brake pad 1209 pivots to be substantially aligned with the wheel 115 at any arrangement thereof, thereby optimizing the braking force upon engagement of the brake pad 1209 against the wheel 115.A service cart, when loaded with an electric battery, may have a considerable weight that is difficult to move. It would thus be advantageous for the service cart to be configured to receive assistance from an external tool suitable for reducing the effort required by a skilled technician to move the overall weight of a loaded cart, such as a tow or tow device. FIG. 15 provides a top view of a service cart 100 showing an arrangement of tow couplings 117 around the service cart 100 at a different angle than that of FIG. 1. As shown above with respect to FIG. 1, FIG. 15 illustrates an embodiment in which the plurality of tow couplings 117 are operatively disposed on one of a first set of strut members 105 or a first set of cross members 109, however, other embodiments may have other configurations without departing from the teachings disclosed herein. Other such embodiments may include configurations having a different number of tow couplings 117, other arrangements of one or more tow couplings 117, or a combination thereof. FIG. 15 also illustrates a top view of an external tow device 1500 operatively coupled to one of the tow hitches 117. In the illustrated embodiment, the external tow device 1500 includes a hand-operated electric tow device, however, other devices may be used without departing from the teachings disclosed herein. Other such external tractors may include an electric tractor, a hydraulic tractor, a pneumatic tractor, or a tractor operated using an internal combustion engine, or any other similar device driven by a mechanism known to those of ordinary skill in the art without departing from the teachings disclosed herein. In some configurations, the external towing device may be configured as a "tractor" that is well suited for applying a pulling force in an orthogonal direction away from the frame of the service cart 100, but in the illustrated embodiment, the external towing device is sufficient to provide such a force as well as a pushing force in an orthogonal direction to the service cart 100. The external towing device may be advantageously configured to provide sufficient external force to move the cart under load when the brakes of the wheels 115 (see FIG. 1 ) are disengaged. By way of example and not limitation, the external towing device 1500 may be operable to provide an external force sufficient to move loads of at least 1000 lbs, but may also be operable to provide external forces sufficient to move loads of at least 3000-5000 lbs without departing from the teachings disclosed herein.FIG. 15 also illustrates a pull handle 1501 of the external tow device 1500 that may be used by a skilled artisan to apply pushing / pulling forces to the service cart 100 that are amplified by the external tow device 1500, as well as to maneuver the external tow device to deliver such forces in a desired orientation for moving the service cart 100 in a desired direction. In the illustrated embodiment, multiple external tractors 1500 may be coupled to individual tow couplings 117, thereby allowing multiple skilled artisans to use multiple such devices to move the cart under load. Such an arrangement may advantageously allow a carriage subjected to a very heavy load to be moved using external tractors individually unable to move the total weight of the loaded carriage, thereby improving the safety for the skilled personnel and the life of the external tractors. In the illustrated embodiment, the external tow device is releasably coupled to the tow hitch 117 and may be releasably coupled to one of the tow hitch 117 in this embodiment or other embodiments without departing from the teachings disclosed herein.FIG. 16A includes a large view of the components of the tow hitch 117 and the external tow device 1500. The tow hitch 117 includes a pair of hitch flanges 1607 that are used to provide a brace for the hitch components of the external tow device 1500. Each of the coupling flanges 1607 comprises an elongated hole 1609. The releasable coupling of the external towing device 1500 is achieved via pin coupling using a coupling bolt 1611, wherein the slots 1609 are substantially aligned to receive the coupling bolt 1611 inserted through each of the coupling flanges 1607. Additionally, during coupling of the external tow device 1500 to the service cart 100, the coupling pin 1611 is inserted through a number of pin receptacles 1613 of the external tow device 1500, each pin receptacle 1613 having a pin hole 1615 configured to receive the coupling pin 1611 and substantially aligned to allow insertion of the coupling pin 1611 through both during coupling.The bolt receivers 1613 are mounted on a coupling bracket 1617 which includes a bracket collar 1619 operatively coupling the coupling bracket 1617 to the remainder of the external towing device 1500. The hitch mount 1617 further includes a receiving surface 1621 operable to cooperate with a member of the service cart 100 when the external tow device 1500 is coupled to the tow hitch 107. In this illustration, the particular member is a cross member 109, but the coupling bracket 1617 is also suitable for cooperating with the strut members 105 (see FIG. 1 ) of the service cart 100 without departing from the teachings disclosed herein.The receiving surface 1621 further includes a number of pressure ramps 1623 configured to provide cushioning and specific friction between the receiving surface 1621 and the cross-member 109 or the strut member 105 of the service cart 100 during coupling. In the illustrated embodiment, the pressure ramps 1623 provide some advantages in coupling the service cart 100 to the external tow device 1500. In a first advantage, the shape of the pressure ramps 1623 helps gradually transfer weight from the service cart 100 to the external tow device 1500. In a second advantage, the material composition of the pressure ramps 1623 may be selected to control the friction between the receiving surface 1621 and the service cart 100 during coupling. By way of example and not limitation, the pressure ramps 1623 may be made of a polymer in the illustrated embodiment, but other materials may be used in other configurations without departing from the teachings disclosed herein. The material may be selected to minimize friction between the service cart 100 and the receiving surface 1621 during coupling and decoupling, yet still sufficient to provide effective transfer of power from the external tow device 1500 to the service cart 100 when coupled. In an additional third advantage, by such a material selection, scratches or other cosmetic damage to the parts of the service cart 100 that contact the pressure ramps 1623 may be minimized while cushioning and friction is increased compared to a metal component, such as the receiving surface 1621.The increased cushioning between the receiving surface 1621 and the pressure ramps 1623 advantageously stabilizes the coupling and further protects the cosmetic appearance and structural integrity of the service cart 100 and the clutch mount 1617 while also assisting in the reduction of corrosion in both of these by surface defects due to frictional contact, thereby advantageously improving the service life of both the service cart 100 and the external tow device 1500. Additional aspects of the pressure ramps 1623 are described below with reference to FIG. 17.In the illustrated embodiment, the clutch mount 1617 includes the coupling components of the external tractor 1500, while the mount collar 1617 couples the clutch mount 1617 to the drive components of the external tractor. The drive components include a series of simple wheels 1631 operable to provide a rolling force in a direction tangential to their rotation. The external tow device 1500 further includes a steering wheel 1633 operable to allow a skilled technician to steer the external tow device 1500. The steering wheel 1633 is a caster operable to pivot and provide pivot adjustments in response to pivot forces applied by a skilled operator to a tow device handle 1501 (not shown, see FIG. 15 ). In combination, simple wheels 1631 and steering wheel 1633 are operable to allow a user to manipulate both the external tow device 1500 and service cart 100 (when coupled thereto) by applying sliding and pulling forces at various angles with respect to an axis defined by coupling pin 1611 upon coupling. These forces are transmitted from the tractor handle 1501 to the wheels via a handle shaft 1635.FIG. 16B is an illustration of an external tow device 1500 during active coupling to the tow hitch 117. In the illustrated embodiment, the coupling pin 1611 is inserted through all of the coupling flanges 1607 and pin receivers 1613, and the pressure ramps 1623 (not shown) have been coupled to the underside of the cross member 109. The illustrated coupling is a releasable coupling, and the hitch bolt 1611 may be removed from the tow hitch 117 at any time to release the external tow device 1500, thereby allowing the pressure ramps 1623 to disengage from the underside of the cross-member 109 when the external tow device 1500 is pulled away from the frame of the service cart 100.It is further noted that external tow device 1500 includes a drive source 1637 suitable for applying rotational forces to simple wheels 1631 in response to sliding or pushing forces being applied via tow device handle 1501. In the illustrated embodiment, the drive source 1637 is disposed in an L-curve of the handle shaft 1635, however, other embodiments may include other arrangements without departing from the teachings disclosed herein. In the illustrated embodiment, the propulsion source 1637 is shown transparently to avoid obscuring other components of the external tow device 1500. In the illustrated embodiment, the power source 1637 may include an electric motor, but other embodiments may include other configurations without departing from the teachings disclosed herein. Other such external embodiments may include a hydraulic system, a pneumatic system, an internal combustion engine, a hybrid engine, or any other similar device powered by a mechanism known to those of ordinary skill in the art without departing from the teachings disclosed herein. In the illustrated embodiment, the external tow device 1500 may provide sufficient force to move a service cart that weighs more than 1000 lbs. when loaded. In some embodiments, the external tow device 1500 may provide sufficient force to move a service cart that weighs 3000-5000 lbs. when loaded without departing from the teachings disclosed herein.FIGS. 17A and 17B provide cross-sectional views of portions of the service cart 100 and portions of the external tow device 1500 in a plane bisecting the tow hitch 117 at an equal distance between each of the hitch flanges 1607. The plane shown also bisects the external towing device 1500 at an equal distance between each of the simple wheels 1633. FIG. 17A provides an illustration of the two devices directly prior to coupling and FIG. 17B provides an illustration of the two devices when coupled.In FIG. 17A, the handle shaft 1635 extends upwardly into the bracket collar 1619 of the clutch bracket 1617, thereby allowing the clutch bracket 1617 to pivot about an axis defined by the longitudinal center of the extension. In the retainer collar 1619, the compression spring 1701 provides an upward normal force to the bottom of the receiving surface 1621, thereby urging the compression ramps 1623 upward. The upward normal force of compression spring 1701 advantageously allows a lower minimum coefficient of friction between pressure ramps 1623 and service cart 100 in direction 1702, thereby simplifying the coupling and decoupling process while maintaining a baseline amount of traction between them when coupled. When the external towing device 1500 is moved in the direction 1702 to effect the coupling, the weight of the service cart 100 is received by the pressure ramps 1623, thereby generating a downward force 1704 that opposes the upward normal force of the compression spring 1701.In FIG. 17B, the coupling bolt 1611 is inserted into all the coupling flanges 1607 and bolt receivers 1613, while the underside of the cross member 109 transfers a part of the weight of the service cart 100 to the pressure ramps 1623, whereby the compression spring 1701 is compressed to some extent and the stability of the bolt fastening mechanism via the friction between the pressure ramps 1623 and the cross member 109 is increased. Although the compression spring 1701 is compressed in this illustration, it is noted that the coupling bracket 1617 may still pivot about the extension axis of the handle shaft 1635, thereby allowing a skilled worker to adjust the angle at which the pushing or pulling force is applied to the service cart 100 relative to the coupled external towing device 1500. As shown above with reference to FIG. 16, this coupling is a releasable coupling and the coupling pin 1611 can be removed at any time to allow the external towing device 1500 to be disconnected from the service cart 100.While exemplary embodiments have been described above, it is not intended that these embodiments describe all possible forms of the disclosed apparatus and method. Rather, the terms used in the specification are words of representation rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various implementation embodiments may be combined to form further embodiments of the disclosed concepts.

Claims

A service cart (100) comprising: a frame (103) comprising a number of first strut members (105a; 105b), a number of second strut members (105c; 105d), a number of support members (107), a number of first cross members (109a; 109b; 109c), and a number of second cross members (109d; 109e; 109f), wherein all support members (107) are disposed between a first strut member (105a; 105b) and a second strut member (105c; 105d), all first cross members (109a; 109b; 109c) are disposed between respective ones of the number of first strut members (105a; 105b), and all second cross members (109d; 109e; 109f) are disposed between respective ones of the number of second strut members (105c; 105d); a first number of wheels (115), each of the wheels (115) operatively coupled to at least one of the first brace members (105a; 105b) or one of the first cross members (109a; 109b; 109c); and a second number of wheel locks with a brake, each of the wheel locks operatively coupled to one of the first number of wheels (115) and configured to apply a braking force to its respective wheel (115) when its brake is applied; wherein at least one of the second cross members (109d; 109e; 109f) is an adjustable cross member (111) configured for adjustable placement between two of the second brace members (105c; 105d) longitudinally perpendicular to each of the second brace members (105c; 105d); 105d) having a predetermined degree of tolerance, and wherein each of the adjustable cross members (111) includes a support pad (501) configured to provide a support force in a direction substantially parallel to the longitudinal orientation of the support members (107) having a predetermined degree of tolerance.The service cart (100) of claim 1, wherein each of the support shelves (501) is configured for adjustable longitudinal placement with respect to its respective second cross member (109d; 109e; 109f).The service cart (100) of claim 2, wherein each of the support shelves (501) is coupled to a slide block (511), each slide block (511) operable to restrict positioning of the support shelf (501) when the support shelf (501) is under load and to allow adjustment of the positioning of the support shelf (501) longitudinally with respect to its respective second cross member (109d; 109e; 109f) when the support shelf (501) is not under load.The service cart (100) of claim 3, wherein each sliding block (511) comprises a sliding spring (619).The service cart (100) of claim 3, wherein each of the second cross-members (109d; 109e; 109f) comprises a locking channel (615) having a series of channel teeth (617) longitudinally disposed in the channel, and wherein each of the support pads (501) comprises a locking pin (613) disposed in the travel channel of its respective second cross-member (109d; 109e; 109f), wherein the snap lock is configured to lock the locking pin (613) between two of the channel teeth (617) when the support pad (501) is under load.The service cart (100) of claim 3, wherein each sliding block (511) is at least partially disposed in a cross member (109).The service cart (100) of claim 1, wherein the support shelves (501) comprise a shelf shaft (505) operable to allow a user to adjust the height of the support shelf (501) relative to the frame (103).The service cart (100) of claim 7, wherein the height adjustment mechanism comprises a jackscrew (507).The service cart (100) of claim 1, wherein the frame (103) and the support shelves (501) are configured to support a load of at least 3000 lbs.The service cart (100) of claim 9, wherein the frame (103) and the support pads (501) are configured to support a load of at least 5000 lbs.The service cart (100) of any preceding claim, further comprising: a handle mount (1013) coupled to a first strut member (105a; 105b) or a first cross member (109a; 109b; 109c); and a handle (113; 114) configured to be releasably coupled to the handle mount (1013), wherein the handle (113; 114) comprises a push rod (1019), and the brakes are selectively applied according to the position of the push rod (1019).The service cart (100) of claim 11, wherein each of the brakes comprises a normally engaged configuration.The service cart (100) of any preceding claim, wherein the first cross members (109a; 109b; 109c) comprise a locking hinge (209), and a number of the second cross members (109d; 109e; 109f) are second folding cross members comprising a locking hinge (209), wherein the first cross members (109a; 109b; 109c) and the second folding cross members are each operable to adjust their respective coupling angles to their respective strut members (105) when the locking hinge (209) is released.The service cart (100) of claim 13, wherein at least one of the locking hinges (209) comprises a spring-loaded pin lock (211).The service cart (100) of any preceding claim, further comprising a tow hitch (117) disposed on the frame (103), the tow hitch (117) operable to releasably couple the frame (103) to an external tow device (1500) with a hitch mount (1617) by coupling the tow hitch (117) and the hitch mount (1617).The service cart (100) of any preceding claim, wherein at least one of the second cross members (109d; 109e; 109f) comprises a support pad (501) configured to provide a support force in a direction substantially parallel to the longitudinal orientation of the support members (107) with a predetermined degree of tolerance, the support pad (501) having a shank collar (801) with a collar opening (805) configured to receive a break pin (809), the break pin (809) configured to be inserted into the collar opening (805) and break when subjected to a shear force greater than a predetermined threshold.The service cart (100) of claim 16, wherein the break pin (809) is configured to generate an audible signal when broken.The service cart (100) according to any one of the preceding claims, wherein the frame (103) comprises two first strut members (105a; 105b), two second strut members (105c; 105d), six support members (107), three first cross members (109a; 109b; 109c) and at least five second cross members (109d; 109e; 109f), wherein at least two of the second cross members (109d; 109e; 109f) are adjustable cross members (111).

Images