REMOTELY OPERATED CLAMP DEVICE.

Abstract

This disclosure provides remotely operated clamping devices for facilitating the installation, removal, and other handling of wheels (also known in the art as rims) and tires for large vehicles. The clamping devices generally include a coupling mechanism, a gripping mechanism, an operable drive linkage for moving the gripping mechanism between an open and a closed position, an actuator for activating the drive linkage, a transmitter for sending command signals to the clamping devices to open or close the gripping mechanism, and a receiver for receiving such command signals.

Description

REMOTELY OPERATED CLAMP DEVICE Cross-reference to related applications Not applicable. Field of invention The present invention is generally directed to clamp devices that can be remotely operated to facilitate the installation, removal and other handling of wheels (also known in the art as rims) and tires for large vehicles. Background of the invention Large vehicles, such as backhoes, excavators, tractors, graders, trenchers, semi-trailers, and the like, are often equipped with wheels whose diameters are greater than a person's height and with tire / wheel combinations weighing several thousand kilograms. Such wheels cannot be handled manually. Furthermore, even with mechanical lifting assistance, it can be difficult and dangerous to maneuver very heavy wheels to properly align them with hubs, connectors, and other fittings necessary for mounting and removing them from a vehicle. These difficulties are often exacerbated by a lack of workspace around the wheel and the need to work on a vehicle in the field rather than in a workshop. For example, with current off-road (OTR) wheel removal methods, a tire handler is needed to hold the wheel while a technician removes / installs the last two / first two lug nuts. The handler prevents the wheel from tipping over and injuring the technician. However, it is unsafe for the technician to remove / install the remaining lug nuts while the tire handler is in the work area, as the tire handler is a large piece of heavy machinery with the potential to injure the technician as well. Therefore, it would be desirable to have a device that could be remotely operated by the technician to assist in the process of removing and installing the OTR wheels on the vehicle in order to improve the overall safety of the process. Brief description of the invention According to one embodiment, this disclosure provides a remotely operated gripper device for securely holding a wheel bolt. The gripper device generally includes: a gripping mechanism sized and adapted to grip the wheel bolt, the gripping mechanism being movable between an open position and a closed position; a drive linkage that engages the gripping mechanism, the drive linkage being selectively movable between a first position and a second position, wherein the gripping mechanism is in the open position when the drive linkage is in the first position and the gripping mechanism is in the closed position when the drive linkage is in the second position; and an actuator. MAa.ZUZZU 1 uo / o that couples to the drive linkage and is configured to selectively move the drive linkage to the first and second positions; a coupling mechanism for attaching the gripper device to the wheel; a transmitter for transmitting operating commands entered by a user; and a receiver for controlling the actuator and causing the actuator to selectively move the drive linkage to the first and second positions in response to the operating commands. According to some embodiments, the gripper device may further include a signal to indicate the position of the gripping mechanism and a height-adjustable platform for raising and lowering the gripper device. In another embodiment, a method is provided for temporarily securing a wheel mounted on a hub of a large vehicle, the hub having a plurality of bolts on which the wheel is mounted. The method includes the following steps: (a) attaching the clamp device of this disclosure by means of the wheel-attachment mechanism on and in line with a bolt selected from the plurality of wheel bolts; (b) transmitting a first operating command by means of the transmitter to the receiver to cause the actuator to move the drive linkage to the second position, thereby moving the gripping mechanism to the closed position to hold the wheel mounted on the hub; (c) transmitting a second operating command by means of the transmitter to the receiver to cause the actuator to move the drive linkage to the first position, thereby moving the gripping mechanism to the open position; and (d) releasing the wheel linkage mechanism. Brief description of the drawings The structure, operation, and advantages of the present invention will become more apparent after consideration of the following description taken in conjunction with the accompanying figures. The figures are intended to be illustrative, not limiting. Certain elements in some of the figures may be omitted or illustrated without scale for clarity. Cross-sectional views may be in the form of "cuts" or "close-up" cross-sectional views, omitting certain background lines that would otherwise be visible in a "true" cross-sectional view, for clarity. Figure 1 is an exploded perspective view of a wheel mounting assembly. Figure 2 is a side perspective view of the clamp device according to a first modality in a closed position. Figure 3 is a side perspective view of the clamp device of Figure 2 in an open position. Figure 4 is a cross-sectional view of the clamp device of Figure 2 in a closed position. Figure 5 is a cross-sectional view of the clamp device of Figure 2 in an open position. Figure 6 is a side perspective view of the clamp device of Figure 2 attached to a wheel. Figure 7 is a side perspective view of the clamp device of Figure 2 attached to a wheel and gripping a hub bolt with a section of the wheel and tire removed for clarity. Figure 8 is a side perspective view of a gripper device according to a second modality in a closed position. Figure 9 is a side perspective view of the clamp device of Figure 8 in an open position. Figure 10 is a side view of the clamp device of Figure 8 attached to a wheel and in a closed position securely holding a bolt. Figure 11 is a side perspective view of a gripper device according to a third modality in a closed position. Detailed description of the invention This disclosure relates to a clamping device configured for remote opening and closing, which can be used as a substitute for lug nuts during the installation and removal of wheels on large vehicles. The clamping device is characterized by a drive link attached to a gripping mechanism that is selectively movable between a first position, which opens the gripping mechanism, and a second position, which closes the gripping mechanism. The clamping device further includes an actuator, a transmitter, a receiver, and a coupling mechanism. The actuator is coupled to the drive link and selectively moves the drive link between the first and second positions. The transmitter transmits operating commands, entered by a user, to the receiver.The receiver controls the actuator and causes the actuator to selectively move the drive linkage between the first and second positions in response to operating commands from the transmitter. The coupling mechanism allows for selective attachment of the clamping device to a wheel. The clamping device described herein offers numerous advantages over the prior art. For example, because the clamping device can be safely attached to and released from the wheel bolts remotely by a user, the possibility of the wheel tipping over and injuring the user during installation and removal is eliminated. Furthermore, the clamping device allows technicians to position themselves away from the tire handler during the installation and removal process, further improving workplace safety. With reference to Figure 1, a typical wheel mounting assembly, such as that used on a tractor or other large vehicle, to which the clamping device of this disclosure may be attached, is shown. The wheel mounting assembly may generally include a brake drum 2 mounted on a hub 3. A plurality of externally threaded bolts or screws 6 are mounted on and extending from the hub 3. The bolts 6 may be configured in a generally circular arrangement, each being circumferentially separated from the others. In the embodiment shown, there are ten bolts. However, the number of bolts may vary. Bolt holes 8 are formed in the wheel 4 and receive the bolts 6 when the wheel 4 is mounted on the hub 3 and drum 2. Internally threaded studs 9 are provided for each bolt 6 to secure the wheel to the hub 3 and drum 2. Now, with reference to Figures 2 through 7, according to one embodiment, a clamp device 10 is shown that is capable of replacing a lug nut during the installation / removal of a large vehicle wheel and is operable to open and close remotely to improve the overall safety of such installation / removal. The clamp device 10 includes a gripping mechanism 25, shown as a pair of pivotally connected jaws 25a and 25b, movable between an open position in which the jaws are separated to accommodate the lug nut, and a closed position in which the jaws are brought together and define a housing 12 for the lug nut to grip and hold it securely. The housing 12, defined by the pair of jaws in the closed position, is adapted to the contour of the area for gripping the lug nut. In this particular case, this contour is circular, and therefore the housing 12 is shown as a circle.For this purpose, each jaw has, on its front end side, a recess in the shape of an arc whose radius corresponds to that of the bolt. The clamping device 10 is designed so that the pair of jaws 25a, 25b can be interchanged with other pairs of jaws that define other sizes and shapes of housings 12 to accommodate different bolt sizes, shapes, and pitches. In this embodiment, the inner surfaces 25c of the jaws are shown as threaded, although in other embodiments, these surfaces may be unthreaded or relatively smooth. Each jaw 25a, 25b is conveniently made of a metal or aluminum alloy. The gripper device 10 also includes a connecting mechanism 22 by means of which the gripper device 10 can be attached to the wheel 4. In the embodiment shown in Figures 2 to 7, the connecting mechanism 22 comprises a magnet. The magnet can be any type of magnet known to those skilled in the art that is operable to provide a strong external magnetic field for bonding with an external ferromagnetic material. For example, the magnet can be an interchangeable magnetic device. Such interchangeable magnetic devices generally include a magnet housing 22a, a first permanent magnet, and a second permanent magnet (not shown), the first and second permanent magnets being diametrically polarized. The first and second permanent magnets are mounted within the magnet housing 22a such that the first and second permanent magnets can be rotated relative to each other.A lever 22b can be used to cause the relative rotation of the first and second permanent magnets. For example, when the first and second permanent magnets are positioned relative to each other such that a north and south pole of the first magnet are in substantial alignment with the respective north and south poles of the second magnet, the magnetic device presents a relatively strong external magnetic field and can be secured to wheel 4. Lever 22b can be rotated to cause the relative rotation of the first and second magnets such that the north pole of the first magnet is in substantial alignment with the south pole of the second magnet and vice versa, and therefore the magnetic device will present a relatively weak external magnetic field that allows the magnetic device to be released from wheel 4.Lever 22b can be positioned and configured in housing 22a to allow it to be accessible from the rear of the clamp device 10. The gripper device 10 further includes a drive linkage 24, an actuator 26, a transmitter 28, and a receiver 29. The drive linkage 24 is coupled to the gripping mechanism 25. In the embodiment shown in Figures 2 to 7, the drive linkage 24 is in the form of a collar that is coupled and configured to be movably positioned over the pair of jaws 25a, 25b. As mentioned previously, the drive linkage 24 is selectively movable between a first position and a second position. In the first position, the drive linkage 24 moves the gripping mechanism 25 to the open position, as shown in Figure 3. In the second position, the drive linkage 24 moves the gripping mechanism 25 to the closed position, as shown in Figure 2.The actuator 26 engages the drive linkage 24 at a rear portion 31 and moves the drive linkage 24 between the first and second positions along a linear axis. The actuator 26 can be any well-known electrical, mechanical, hydraulic, or pneumatic device capable of moving or controlling something. In the embodiment shown in Figures 2 to 7, the actuator 26 is an electromagnetic actuator. The electromagnetic actuator generally includes an electromagnet 26a, a battery 26b, a movable magnetic member 26c, and a spring 26d. The electromagnet 26a will generally include an electrical coil wound around a stationary magnetic member (not shown). The battery 26b can be any type of battery well-known to those skilled in the art, such as a non-rechargeable lithium-ion battery (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium-ion polymer, nickel-metal hydride, nickel-cadmium, nickel-hydrogen, nickel-zinc, or zinc-silver.In general, the battery 26b can be positioned near the rear of the clamping device 10 for ease of access. The movable member 26c, shown as a bar, is directly coupled with the rear portion 31 of the drive linkage 24. Figure 2 represents a condition in which the electric coil is not energized. Under this condition, the movable member 26c is held in a first state with the drive linkage 24 in the second position by the polarizing force caused by the spring 26d. Under this condition, if the electric coil is supplied with a predetermined current by means of the battery 26b, an electromagnetic attraction force greater than the polarizing force generated by the spring 26d is generated between the stationary magnetic member and the movable member 26c.The movable member 26c is switched to a second state as shown in Figure 3, in which the movable member 26c is attracted to the stationary magnetic member. In accordance with this movement, the drive linkage 24 is mechanically actuated and moves from the second position to the first position. The actuator 26 will return to the first state shown in Figure 2 when the electrical coil is free of the energizing current supplied by the battery 26b. The transmitter 28 produces an operating command, in the form of a signal, when activated by the user. Preferably, a wireless transmitter is used such that the signal produced by the transmitter 28 is in the form of wireless energy, such as laser, infrared, microwave, or radio wave energy. The receiver 29 controls the actuator 26 and causes the actuator 26 to selectively move the drive link 24 to the first and second positions in response to the operating commands from the transmitter 28. Such transmitters and receivers are well known in the field and will not be described in detail herein. The various internal components of the gripper device 10 can be held together by a frame 20. One or more of the internal components of the gripper device can also be housed together in an outer casing (not shown). In some embodiments, the frame and outer casing can be constructed from a rigid, durable material so that moisture and potential impacts to the frame and outer casing do not damage the internal components of the gripper device 10. Such materials may include plastics, rubber, silicone, metals, alloys, treated nylon, fabric, canvas, leather, and combinations thereof. In operation, the frame 20, which includes the gripping mechanism 25, drive link 24, actuator 26, and receiver 29, is mounted on the wheel 4 adjacent to a pin by means of the connecting mechanism 22. The rear portion 31 of the drive link 24 engages with the actuator 26, and the gripping mechanism 25 is in the open position. A press of button 34 on the transmitter 28 sends a first command signal to the receiver 29. In response to the first command signal, the receiver 29 causes the actuator 26 to move the drive link 24 to the second position, thereby moving the gripping mechanism 25 to the closed position to securely grip the wheel pin.The gripping mechanism 25 is held closed by means of the drive linkage 24 and actuator 26 until button 34 on the transmitter 28 is pressed again, after which the actuator 26 moves the drive linkage 24 to the first position, thereby moving the gripping mechanism 25 to the open position. Alternatively, more than one press, such as two presses of button 34 on the transmitter, sends a second command signal to the receiver 29. In response to the second command signal, the receiver 29 causes the actuator 26 to move the drive linkage 24 to the first position, thereby moving the gripping mechanism 25 to the open position.To further ensure that the gripping mechanism 25 remains in the closed position, the transmitter 28 and receiver 29 can be programmed so that the actuator 26 moves the drive linkage 24 to the second position every second outside of a programmed time (e.g., a 15-second cycle). In some configurations, there may be two buttons 34, each requiring a press to send command signals to the receiver 29 to prevent accidental operation. The gripping mechanism 25 can also be manually moved between the open and closed positions at any time by the user, for example, using a toggle switch connected to the actuator 26 (not shown). Now, with reference to Figures 8 to 10, a gripper device 80 is shown according to a second embodiment. The gripper device 80 in Figures 8 to 10 may be substantially similar in design and operation to the gripper device 10 shown in Figures 2 to 7 and described above for securely gripping a wheel bolt 6 of a wheel 4 and includes a joining mechanism 82 (shown as a pair of interchangeable handles), a drive linkage 84 (shown as a collar), a gripping mechanism 85 (shown as a pair of jaws 85a, 85b), an actuator 86, a transmitter 88 (with a push button 94), and a receiver 89. In this embodiment, the gripper device 80 further includes one or more springs 95, a lower base 96, an upper base 98, and a signaling means 90. The springs 95 may be extension springs and are configured and adapted to suspend the gripping mechanism 85 in such a way that the gripping mechanism 85 is operable to self-align on the bolt as it moves to the closed position. The lower base 96 and the upper base 98, like the frame and housing described above for the gripper device 10, may be constructed from a rigid and durable material such that moisture and potential impacts to them will not damage the internal components of the gripper device 80. Such materials may include plastics, rubber, silicone, metals, alloys, treated nylon, fabric, canvas, leather, and combinations thereof. Signaling means 90 can be used to indicate the position of at least one of the jaws 85a, 85b in a predetermined position (e.g., the open or closed position) or the position of the drive linkage 84 (e.g., the first or second position). For example, signaling means 90 may include a metal strip mounted on one of the jaws 85a, 85b, or drive linkage 84 to move with them, a circuit having a normally open switch in the path of movement of the metal strip, and an indicator light. This arrangement is such that the indicator light will be energized and illuminated in response to the metal strip closing the switch in a position corresponding to the closed position of the jaws 85a, 85b, or in a position corresponding to the second position of the drive linkage 84 (as shown in Figure 8).Similarly, the indicator light is not energized and does not illuminate when the switch is open, which corresponds to the open position of jaws 85a, 85b or the first position of drive linkage 84 (as shown in Figure 9). Now, with reference to Figure 11, a clamp device 110 is shown according to a third embodiment. The clamp device 110 in Figure 11 may be substantially similar in design and operation to the clamp devices 10 and 80 shown in Figures 2 to 10 and described above, and may further include a height-adjustable platform 111 that can be manipulated to raise and lower the clamp device to a height that facilitates attaching the clamp device 110 to a wheel bolt. The height-adjustable platform 111 includes an upper platform 112 to which the clamping device 110 is secured, a lower platform 114 (similar to the base 96 shown in Figures 8 and 9), and a scissor link 116 coupled between the lower platform 114 and the upper platform 112. The scissor link 116 may include left and right scissor legs 117, 118 that pivotally connect together at their midsections to create an X centered on a pivot access and release mechanism 119. The left scissor leg 117 may include an opening positioned above its midsection. The right scissor leg 118 may include a curved piece 118a attached to its upper surface and positioned below its midsection, which includes a plurality of openings. The left scissor leg opening 117 is sized and shaped similarly to the right scissor leg openings 118.The unlocking mechanism 119, shown as a pin, is sized and configured to slide into the left scissor leg opening 117 and right scissor leg openings 118 when such openings are aligned. Therefore, in operation, the height-adjustable platform 111 can be locked in the position when the pin is inserted into the openings of the left and right scissor legs 117, 118. When it is desired to raise or lower the upper platform 112 relative to the lower platform 114, the pin is first removed from the openings of the left and right scissor legs 117, 118. Then, the upper platform 112 is raised or lowered by aligning the opening of the left scissor leg 117 with one of the openings of the right scissor leg 118, and the pin is reinserted into the openings. Other types of scissor lifting mechanisms known to those skilled in the art may be used instead of the mechanism described herein and will not be described in further detail. According to another embodiment, this disclosure provides a method for using the clamping device instead of lug nuts to remotely and temporarily secure and release the clamping mechanism of a wheel stud during wheel removal and installation. The wheel may be any wheel known and used in connection with large vehicles (e.g., power shovels, backhoes, tractors, graders, trenchers, semi-trailers, and the like), such as off-road (OTR) wheels, agricultural wheels, or commercial wheels. As a first step in removing the wheel from the large vehicle, at least one lug nut, preferably two, are removed from their corresponding studs, such as the studs located at the 3 o'clock and 9 o'clock positions on the hub. Next, the clamping devices described herein are attached to the wheel by means of their attachment mechanisms so that their gripping mechanisms, in the open position, are positioned over the exposed studs. The user can then transmit a wireless signal to the receivers of each clamping device via the transmitter, causing the actuators of each clamping device to move their drive links from the first position to the second position, thereby moving the gripping mechanisms from the open position to the closed position.The user can confirm that the lug nuts are securely attached and engaged with the gripping mechanisms by checking the position of the drive linkages on each gripper and / or whether their indicator lights are illuminated. The user can then remove the remaining lug nuts and move them away from the work area. A tire handler can then be used to grip the wheel. The user can then transmit a second signal via the transmitter to the receivers on the gripping devices, causing their actuators to move the drive linkages from the second position to the first position, thus opening the gripping mechanisms. The tire handler can then remove the wheel from the large vehicle and position it horizontally on the floor. Each gripper can be removed from the wheel by uncoupling its wheel-mounting mechanisms. When installing the wheel on the larger vehicle, two clamping devices can be secured to the wheel in line with, for example, the 3 o'clock and 9 o'clock bolt holes. The positioning does not need to be exact, as the gripping mechanism is designed to self-align to the bolt after engagement. The user can then leave the work area to allow the tire manipulator to grip and position the wheel on the larger vehicle. The user can then remotely transmit a signal to the receivers of each clamping device via the transmitter, causing the actuator to move the drive links from the first position to the second position, thereby closing the gripping mechanisms of each clamping device on the corresponding bolts.Next, the user can confirm that each gripper is securely attached to its respective lug nut by verifying that the drive linkage has moved to the second position and that the indicator lights on each gripper are illuminated. The tire manipulator can then be released from the wheel and moved away from the work area. The user can then install lug nuts on each lug nut, except for the two lug nuts that accommodate the two grippers. Next, the user can send a second signal to the receivers on each gripper, causing the actuator to move the drive linkages from the second position to the first position, thereby opening the gripping mechanisms of each gripper. Finally, the user can remove each gripper from the wheel by disengaging its connecting mechanism.Next, the final studs can be installed on the two remaining exposed bolts. While the foregoing is directed to modalities of the present disclosure, additional modalities of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by means of the following claims.

Claims

1. A remotely operated gripper device comprising: a gripping mechanism operable for gripping a bolt of a wheel mounting assembly, the gripping mechanism movable between an open position and a closed position; a drive linkage coupled to the gripping mechanism, the drive linkage selectively movable between a first position and a second position, the gripping mechanism being in the open position when the drive linkage is in the first position and the gripping mechanism being in the closed position when the drive linkage is in the second position; an actuator coupled to the drive linkage and selectively moving the drive linkage to the first position and the second position; an operable attachment mechanism for attaching the gripper device to a wheel of the wheel mounting assembly; a transmitter for transmitting operating commands entered by a user;and a receiver that controls the actuator and causes the actuator to selectively move the drive linkage to the first position and the second position in response to operating commands.

2. The clamping device according to claim 1, wherein the gripping mechanism comprises a pair of pivotally joined jaws.

3. The gripper device according to claim 2, wherein the drive linkage is a collar configured to be movably positioned over the pivotally joined pair of grippers.

4. The clamping device according to claim 1, wherein the actuator is an electromagnetic actuator.

5. The clamping device according to claim 1, wherein the joining mechanism is an interchangeable magnetic device.

6. The gripper device according to claim 1, further comprising an outer casing surrounding at least one of the gripping mechanism, the drive linkage, the actuator, and the receiver.

7. The clamp device according to claim 6, wherein the outer casing is constructed from plastic, rubber, silicone, a metal, an alloy, a treated nylon, fabric, canvas, leather, or a combination thereof.

8. The clamping device according to claim 2, further comprising an indicator light configured to illuminate when the pair of jaws are in the closed position.

9. The clamping device according to claim 1, further comprising at least two springs configured to suspend the gripping mechanism such that the gripping mechanism is operable to self-align on the wheel bolt as it moves to the closed position.

10. The clamping device according to claim 1, wherein the actuator comprises a toggle switch configured and operable such that the drive linkage can be selectively moved to the first and second positions manually.

11. A remotely operated gripper device comprising: a gripping mechanism operable for gripping a bolt of a wheel mounting assembly, the gripping mechanism movable between an open position and a closed position; a drive linkage coupled to the gripping mechanism, the drive linkage selectively movable between a first position and a second position, the gripping mechanism being in the open position when the drive linkage is in the first position and the gripping mechanism being in the closed position when the drive linkage is in the second position; an actuator coupled to the drive linkage and selectively moving the drive linkage to the first position and the second position; a joining mechanism for attaching the gripper device to a wheel of the wheel mounting assembly;an operable height-adjustable platform for raising and lowering to a height that facilitates attachment of the clamping device to the wheel bolt; a transmitter for transmitting operating commands entered by a user; and a receiver that controls the actuator and causes the actuator to selectively move the drive linkage to the first position and the second position in response to the operating commands.

12. The remotely operated gripper device according to claim 11, wherein the height-adjustable platform comprises an upper platform to which the gripper device is secured, a lower platform, and a scissor link coupled between the lower platform and the upper platform.

13. The remotely operated gripper device according to claim 11, further comprising an indicator light configured to illuminate when the gripping mechanism is in the closed position.

14. The remotely operated gripper device according to claim 11, further comprising at least two springs configured to suspend the gripping mechanism such that the gripping mechanism is operable to self-align on the wheel bolt as it moves to the closed position.

15. A method for temporarily securing a wheel mounted on a hub of a wheel mounting assembly, the hub having a plurality of bolts on which the wheel is mounted, the method comprising: (a) attaching the clamping device according to claim 1 by means of the attachment mechanism to the wheel on and in line with a bolt selected from the plurality of wheel bolts; (b) transmitting a first operating command from the transmitter to the receiver to cause the actuator to move the drive linkage to the second position, thereby moving the clamping mechanism to the closed position to secure the wheel mounted on the hub; (c) transmitting a second operating command from the transmitter to the receiver to cause the actuator to move the drive linkage to the first position, thereby moving the clamping mechanism to the open position; and (d) releasing the attachment mechanism from the wheel.

16. A method for temporarily securing a wheel mounted on a hub of a wheel mounting assembly, the hub having a plurality of bolts on which the wheel is mounted, the method comprising: (a) attaching the clamping device according to claim 11 by means of the attachment mechanism to the wheel; (b) manipulating the height-adjustable platform such that the clamping device is over and in line with a selected bolt from the plurality of wheel bolts; (c) transmitting a first operating command from the transmitter to the receiver to cause the actuator to move the drive linkage to the second position, thereby moving the gripping mechanism to the closed position to hold the wheel mounted on the hub;(d) transmitting a second operating command from the transmitter to the receiver to cause the actuator to move the drive linkage to the first position, thereby moving the gripping mechanism to the open position; and (e) releasing the wheel linkage mechanism.

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