Well casing lowering device

Abstract

The utility model relates to a well casing lowering device which comprises a bottom frame, two groups of hoisting mechanisms are arranged on two sides of the bottom frame, a steel wire rope is arranged between the two groups of hoisting mechanisms, two ends of the steel wire rope are respectively wound on the two groups of hoisting mechanisms, and the winding directions of the steel wire rope on the two groups of hoisting mechanisms are opposite. Wherein a driving mechanism with an output shaft is further arranged on the outer side of one group of hoisting mechanism, the output shaft of the driving mechanism is connected with the two groups of hoisting mechanisms through transmission mechanisms respectively, each transmission mechanism comprises a rotating shaft installed on the hoisting mechanism, and the rotating shafts are parallel to the output shaft of the driving mechanism. One end of each rotating shaft is rotationally connected with a first chain wheel, an output shaft of the driving mechanism is sleeved with two second chain wheels, the second chain wheels and the first chain wheels are connected through transmission chains, and inserting and pulling pieces capable of enabling the first chain wheels and the rotating shafts to be relatively fixed are detachably connected between the first chain wheels and the rotating shafts. According to the utility model, the pipe can be conveniently discharged; and the risk of pulling apart the steel wire rope can be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of construction equipment, and particularly relates to a well pipe lowering device. Background Art

[0002] The utility model patent with the publication number of CN216471960U discloses a special pipe-lowering device for well drilling in the existing patent. When this utility model is used, it solves the problems that when placing well pipes, the manual placement method is mainly adopted, resulting in high labor intensity of workers and low operation efficiency.

[0003] However, during the process of lowering the well pipe by this utility model, two sets of driving mechanisms are set to drive the drums to unwind the same steel wire rope respectively to drive the well pipe to descend. In this setting method, when the unwinding speeds of the two sets of driving mechanisms for the steel wire rope are inconsistent, during the descent of the well pipe, the well pipe will find a new balance point on the steel wire rope, which will cause unstable pipe lowering and thus is not convenient for pipe lowering. In addition, after the pipe lowering is completed, when the above utility model withdraws the steel wire rope from the water well, one set of driving mechanism drives the drum to wind up the steel wire rope, and the other set of driving mechanism drives the drum to unwind the steel wire rope. Until the steel wire rope is completely separated from the unwinding drum, the steel wire rope can be completely wound on the winding drum. However, when the winding speed is greater than the unwinding speed, the steel wire rope will be continuously in a tense state, and there is a risk of breaking the steel wire rope, which is not convenient for withdrawing the steel wire rope from the water well. Generally speaking, the above utility model is inconvenient to use. Therefore, there are still disadvantages and deficiencies in the existing technology. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a well pipe lowering device to solve the problems raised in the above background art.

[0005] The technical solutions adopted by the utility model to solve the above problems are as follows:

[0006] A well pipe lowering device includes a horizontally arranged chassis. Two sets of horizontally opposed hoisting mechanisms are installed on both sides of the chassis. A steel wire rope is arranged between the two sets of hoisting mechanisms. The two ends of the steel wire rope are respectively wound around the two sets of hoisting mechanisms, and the winding directions of the steel wire rope on the two sets of hoisting mechanisms are opposite. An outer side of one of the hoisting mechanisms is further provided with a driving mechanism installed on the chassis and having an output shaft. The output shaft of the driving mechanism is respectively connected to the two sets of hoisting mechanisms through transmission mechanisms. Each transmission mechanism includes a rotating shaft coaxially arranged with the hoisting mechanism and fixedly installed at the end of the hoisting mechanism. The rotating shafts are all arranged parallel to the output shaft of the driving mechanism, and the two rotating shafts are located on the same side of the chassis. A first sprocket is sleeved and rotatably connected to the end of each rotating shaft away from the hoisting mechanism. Two second sprockets respectively opposite to the positions of the first sprockets are sleeved and installed on the output shaft of the driving mechanism. The second sprockets and the first sprockets are respectively connected through transmission chains. A pluggable member capable of relatively fixing the first sprocket and the rotating shaft is also detachably connected between the first sprocket and the rotating shaft.

[0007] Further, a fixed tube sleeved on the rotating shaft is coaxially fixedly connected to the side of each first sprocket away from the hoisting mechanism. A plugging groove penetrating the fixed tube is axially formed on the inner wall of the fixed tube along the axial direction of the fixed tube. The end of the rotating shaft away from the hoisting mechanism penetrates the fixed tube and is fixedly connected with a convex block. The pluggable member includes a sleeve slidably sleeved on the rotating shaft and located outside the fixed tube. A plugging block opposite to and adapted to the plugging groove is fixedly connected to the side of the sleeve close to the fixed tube. A sliding groove sequentially penetrating the sleeve and the plugging block is axially formed on the inner wall of the sleeve. The convex block is located in the sliding groove and is slidably connected with the sliding groove.

[0008] Further, a limiting block is fixedly connected to the end of the sliding groove close to the first sprocket.

[0009] Further, a wire guiding mechanism erected on the chassis is arranged inside each set of hoisting mechanisms. Each wire guiding mechanism includes a fixed shaft arranged parallel to the hoisting mechanism. The fixed shafts are all circular shafts, and the two ends of the fixed shafts are respectively connected to the chassis. A wire guiding wheel with a wire guiding groove is also slidably sleeved on each fixed shaft. The two ends of the steel wire rope respectively bypass the wire guiding wheels and are wound on the hoisting mechanisms.

[0010] Further, fixed seats are slidably sleeved on both ends of each fixed shaft. The fixed seats are all fixedly connected to the chassis, and a fixing bolt penetrating the fixed seat is threadedly connected between each fixed seat and the fixed shaft.

[0011] Furthermore, the driving mechanism includes a reducer and a forward and reversible driving motor, the driving motor and the reducer are both installed on the base frame, and the driving motor and the reducer are transmission-connected, and the output shaft of the reducer is respectively connected to the two sets of hoisting mechanisms through the transmission mechanism.

[0012] Furthermore, the hoisting mechanisms are all handbrake type hoists.

[0013] By adopting the above technical solution, the beneficial effects of the utility model are:

[0014] The utility model is based on the existing base frame and also provides two groups of winch mechanisms. The same steel wire rope is provided between the two groups of winch mechanisms, but the number of driving mechanisms is set to one group, and the plug-in piece is provided to control whether the driving mechanism can drive the winch mechanism to rotate. Specifically, when the pipe is lowered, the plug-in piece on the two groups of winch mechanisms is in an inserted state. At this time, the driving mechanism can simultaneously drive the two groups of winch mechanisms to rotate in the same direction through the transmission mechanism. Since the winding directions of the steel wire rope on the two groups of winch mechanisms are opposite, the steel wire rope can be unwound at the same time to drive the well pipe to descend. In this way, when the steel wire rope is unwound, there will be no inconsistent unwinding speed. , which can facilitate the lowering of the pipe; in addition, when the wire rope is drawn out from the water well, the plug-in piece on one of the groups of hoisting mechanisms can be pulled out. At this time, the group of hoisting mechanisms can freely rotate as a driven piece, that is, the driving mechanism can no longer drive the group of hoisting mechanisms to rotate through the transmission mechanism, and then when the driving mechanism is started, the driving mechanism can drive the other group of hoisting mechanisms to rotate in the opposite direction as an active piece to reel in the wire rope, and during the process of reeling in the wire rope, the hoisting mechanism as a driven piece can be driven to rotate to unreel the wire rope, so that the wire rope will not be kept in a taut state continuously, so as to reduce the risk of breaking the wire rope, thereby facilitating the wire rope to be drawn out from the water well. In general, the utility model is easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the utility model;

[0016] Figure 2 It is a structural schematic diagram of some devices of the utility model;

[0017] Figure 3 It is a schematic diagram of the structure of some devices of the utility model in a split state;

[0018] Figure 4 for Figure 3 The schematic diagram of the structure of the middle part of the device;

[0019] Figure 5 It is a schematic diagram of the rotation direction of the first hoisting mechanism and the second hoisting mechanism when the utility model is lowered;

[0020] Figure 6 This is a schematic diagram of the rotation directions of the first hoisting mechanism and the second hoisting mechanism when the steel wire rope is retracted for the utility model.

[0021] Figure 7 This is a schematic diagram of the rotation directions of the first hoisting mechanism and the second hoisting mechanism when the steel wire rope is wound before the next pipe lowering for the utility model.

[0022] Reference numerals: 1, chassis; 2, transmission mechanism; 21, rotating shaft; 22, first sprocket; 23, second sprocket; 24, transmission chain; 3, wire guiding mechanism; 31, fixed shaft; 32, wire guiding wheel; 33, fixed seat; 4, driving mechanism; 41, driving motor; 42, reducer; 5, plug-in member; 51, sleeve; 52, plug-in block; 53, sliding groove; 54, limiting block; 6, first hoisting mechanism; 7, second hoisting mechanism; 8, support seat; 9, drum; 10, handbrake type brake member; 11, steel wire rope; 12, fixed pipe; 13, plug-in groove; 14, convex block. Detailed implementation manners

[0023] To make the objectives, technical solutions and beneficial effects of the utility model clearer, the following further describes the implementation manners of the utility model in detail with reference to the accompanying drawings.

[0024] As Figures 1 to 7 shown, the utility model provides a well pipe lowering device, including a horizontally arranged chassis 1. Two groups of horizontally opposite hoisting mechanisms are installed on both sides of the chassis 1. Specifically, the hoisting mechanisms can both be set as handbrake type hoisting machines in the prior art, that is, each group of hoisting mechanisms includes two support seats 8. The two support seats 8 are vertically installed on the chassis 1, and a drum 9 is rotatably connected between the two support seats 8. One end or both ends of the drum 9 are installed with a handbrake type brake member 10 that can brake the drum 9. When in use, when the handbrake type brake member 10 locks the drum 9, the drum 9 cannot rotate any more, and when the handbrake type brake member 10 releases the drum 9, the drum 9 can rotate normally. A steel wire rope 11 is arranged between the two groups of hoisting mechanisms. The two ends of the steel wire rope 11 are respectively wound around the drums 9 of the two groups of hoisting mechanisms, and the winding directions of the steel wire rope 11 on the two groups of hoisting mechanisms are opposite. Specifically, the winding manner of the steel wire rope 11 is as Figures 5 to 7 shown. A driving mechanism 4 with an output shaft is also arranged on the outside of one group of hoisting mechanisms and is installed on the chassis 1. The driving mechanism 4 can rotate forward and backward.

[0025] The output shaft of the driving mechanism 4 is respectively connected to the two sets of hoisting mechanisms through the transmission mechanism 2. The transmission mechanisms 2 each include a rotating shaft 21 that is coaxially arranged with the hoisting mechanism and fixedly installed at the end of the hoisting mechanism. That is, the rotating shaft 21 is coaxially arranged with the drum 9 and fixedly installed at the end of the drum 9. The rotating shafts 21 are all arranged parallel to the output shaft of the driving mechanism 4, and the two rotating shafts 21 are on the same side of the chassis 1. A first sprocket 22 is sleeved and rotatably connected to each end of the rotating shaft 21 away from the hoisting mechanism. Two second sprockets 23 that are respectively opposite to the positions of the first sprockets 22 are sleeved and installed on the output shaft of the driving mechanism 4. The second sprockets 23 and the first sprockets 22 are respectively connected by transmission chains 24. A plug-in member 5 that can relatively fix the first sprocket 22 and the rotating shaft 21 is also detachably connected between the first sprocket 22 and the rotating shaft 21. The plug-in member 5 can control whether the driving mechanism 4 can drive the hoisting mechanism to rotate. Specifically, when the plug-in member 5 is in the inserted state, the first sprocket 22 and the rotating shaft 21 are relatively fixed. At this time, after starting the driving mechanism 4, the first sprocket 22 can be driven to rotate. During the rotation of the first sprocket 22, since the first sprocket 22 and the rotating shaft 21 are relatively fixed, the rotating shaft 21 can be rotated simultaneously to drive the hoisting mechanism to rotate. When the plug-in member 5 is in the pulled-out state, since the first sprocket 22 and the rotating shaft 21 are rotatably connected, when the driving mechanism 4 is started, the first sprocket 22 can be driven to rotate around the rotating shaft 21. At this time, the hoisting mechanism can freely rotate as a driven member, that is, the driving mechanism 4 can no longer drive the hoisting mechanism to rotate through the transmission mechanism 2.

[0026] During use, the hoisting mechanism close to the driving mechanism 4 is the first hoisting mechanism 6, and the other set of hoisting mechanism is the second hoisting mechanism 7. Before lowering the pipe, the chassis 1 is fixed at a suitable position at the wellhead of the water well. Then, when lowering the pipe, the well pipe is placed vertically on the steel wire rope 11 and aligned with the position of the water well. At this time, the plug-in members 5 on the two sets of hoisting mechanisms are all in the inserted state. Then, when the driving mechanism 4 is started, the driving mechanism 4 can drive the two sets of hoisting mechanisms to rotate in the same direction simultaneously through the transmission mechanism 2. The directions of rotation of the two sets of hoisting mechanisms in the same direction are as shown in Figure 5 shown; and since the winding directions of the steel wire rope 11 on the two sets of hoisting mechanisms are opposite, the steel wire rope 11 can be unreeled simultaneously to drive the well pipe to descend. With this setting method, when unreeling the steel wire rope 11, since the two sets of hoisting mechanisms rotate simultaneously, there will be no situation where the unreeling speeds are inconsistent, thus facilitating the lowering of the pipe.

[0027] In addition, when the wire rope 11 is pulled out of the water well, the plug-in member 5 on the second hoisting mechanism 7 can be pulled out. At this time, the second hoisting mechanism 7 can rotate freely as a driven member, that is, the driving mechanism 4 can no longer drive the second hoisting mechanism 7 to rotate through the transmission mechanism 2. Then, when the driving mechanism 4 is started, the driving mechanism 4 can drive the first hoisting mechanism 6 to rotate reversely as a driving member to wind up the wire rope 11. During the winding process of the wire rope 11, the second hoisting mechanism 7 as a driven member can be driven to rotate to unwind the wire rope 11. At this time, the rotation directions of the two hoisting mechanisms are as shown in Figure 6 ; this can prevent the wire rope 11 from being continuously in a taut state, reducing the risk of breaking the wire rope 11, and thus facilitating the extraction of the wire rope 11 from the water well. Generally speaking, the utility model is convenient to use. Then, when the wire rope 11 is completely separated from the second hoisting mechanism 7, the wire rope 11 can be completely wound around the first hoisting mechanism 6 to complete the rope extraction.

[0028] Before the next pipe lowering, when the wire rope 11 is wound around the second hoisting mechanism 7 again, the plug-in member 5 on the second hoisting mechanism 7 can be in the inserted state, and the plug-in member 5 on the first hoisting mechanism 6 can be in the pulled-out state. Then, when the driving mechanism 4 is started, the driving mechanism 4 can drive the second hoisting mechanism 7 to rotate as a driving member to wind up the wire rope 11. During the winding process of the wire rope 11, the first hoisting mechanism 6 can be driven to rotate as a driven member to unwind the wire rope 11. At this time, the rotation directions of the two hoisting mechanisms are as shown in Figure 7 shown.

[0029] The specific setting method of the plug-in member 5 is as follows: as shown in Figure 1 and Figure 3 and Figure 4 shown, on the side of each first sprocket 22 away from the hoisting mechanism, a fixed tube 12 sleeved on the rotating shaft 21 is coaxially fixedly connected. An insertion slot 13 penetrating the fixed tube 12 is axially opened on the inner wall of the fixed tube 12, and two insertion slots 13 can be opened; one end of the rotating shaft 21 away from the hoisting mechanism penetrates the fixed tube 12 and is fixedly connected with a convex block 14, and two convex blocks 14 can be provided; the plug-in member 5 includes a sleeve 51 slidably sleeved on the rotating shaft 21 and located outside the fixed tube 12. On the side of the sleeve 51 close to the fixed tube 12, two insertion blocks 52 opposite to and adapted to the positions of the insertion slots 13 are fixedly connected. And on the inner wall of the sleeve 51, two sliding slots 53 sequentially penetrating the sleeve 51 and the insertion blocks 52 are axially opened. The convex block 14 is located in the sliding slot 53 and is slidably connected with the sliding slot 53. This can prevent the plug-in member 5 from rotating around the rotating shaft 21, and during the sliding process of the plug-in member 5 along the rotating shaft 21, the two convex blocks 14 and the sliding slot 53 can play a guiding role.

[0030] During use, when the plug-in block 52 is inserted into the plug-in slot 13, the plug-in member 5 is in the inserted state. At this time, there is no relative rotation between the plug-in member 5 and the first sprocket 22. On the contrary, the plug-in member 5 is in the pulled-out state. When the plug-in member 5 is in the pulled-out state, since the first sprocket 22 is rotatably connected to the rotating shaft 21, when the driving mechanism 4 is started, when the first sprocket 22 rotates, it will rotate around the rotating shaft 21. At this time, the driving mechanism 4 can no longer drive the hoisting mechanism to rotate through the transmission mechanism 2; when the plug-in member 5 is in the inserted state, after the driving mechanism 4 is started, when the first sprocket 22 rotates, it can drive the rotating shaft 21 to rotate through the plug-in member 5, thereby driving the hoisting mechanism to rotate.

[0031] When pulling out the plug-in member 5 outward, to prevent the plug-in member 5 from falling off the rotating shaft 21, therefore, as Figure 4 shown, a limiting block 54 is fixedly connected to one end of the sliding groove 53 close to the first sprocket 22. Specifically, during use, during the process of pulling out the plug-in member 5 outward, when the limiting block 54 contacts the convex block 14, the convex block 14 can block the plug-in member 5 to prevent the plug-in member 5 from falling off the rotating shaft 21.

[0032] To improve the stability of the steel wire rope 11 during the retracting and unreeling process, therefore, as Figure 1 and Figure 2 shown, a wire guiding mechanism 3 erected on the chassis 1 is provided inside each hoisting mechanism. The wire guiding mechanism 3 includes a fixed shaft 31 arranged in parallel with the hoisting mechanism, that is, the fixed shaft 31 is arranged in parallel with the drum 9; the fixed shafts 31 are all circular shafts, and both ends of the fixed shaft 31 are respectively connected to the chassis 1. A wire guiding wheel 32 with a wire guiding groove is also slidably sleeved on each fixed shaft 31. Both ends of the steel wire rope 11 respectively bypass the wire guiding wheel 32 and are wound around the drum 9 of the hoisting mechanism. Specifically, during use, the rope body of the steel wire rope 11 is located in the wire guiding groove of the wire guiding wheel 32; during the process of retracting and unreeling the steel wire rope 11, the steel wire rope 11 can drive the wire guiding wheel 32 to rotate around the fixed shaft 31, and since the wire guiding wheel 32 is slidably sleeved on the fixed shaft 31, as the position of the steel wire rope 11 on the drum 9 changes, the wire guiding wheel 32 can also slide along the fixed shaft 31, so that the wire guiding wheel 32 can always guide and support the steel wire rope 11 to improve the stability of the steel wire rope 11 during the retracting and unreeling process.

[0033] The specific setting method of the connection between the fixed shaft 31 and the chassis 1 is as follows: as Figure 1 and Figure 2As shown in the figure, both ends of each fixed shaft 31 are slidably sleeved with fixed seats 33. The fixed seats 33 are fixedly connected to the chassis 1, and a fixing bolt passing through the fixed seat 33 is threadedly connected between each fixed seat 33 and the fixed shaft 31. Specifically, the fixing bolt is not shown in the figure. During use, the fixing bolt is radially parallel to the fixed shaft 31. In this way, when the screw end of the fixing bolt abuts against the fixed shaft 31 inside the fixed seat 33, the position of the fixed shaft 31 can be fixed; when the screw end of the fixing bolt is separated from the fixed shaft 31, the fixed shaft 31 can be pulled outwards. Since the wire guiding wheel 32 is slidably sleeved on the fixed shaft 31, it is convenient to disassemble and assemble the fixed shaft 31 and the wire guiding wheel 32 on the chassis 1.

[0034] The specific setting method of the driving mechanism 4 is as follows: As Figure 1 shown in the figure, the driving mechanism 4 includes a speed reducer 42 and a driving motor 41 that can rotate forward and backward. The driving motor 41 and the speed reducer 42 are both installed on the chassis 1, and the driving motor 41 and the speed reducer 42 are drivingly connected. Specifically, during use, the driving mechanism 4 is externally connected to a power source and a start-stop switch, and according to its own needs, a block brake that can automatically brake the input shaft of the speed reducer 42 can be installed on the chassis 1, or an existing handbrake type brake part 10 can be installed on the input shaft of the speed reducer 42 to improve the braking effect of the driving mechanism 4; the output shaft of the speed reducer 42 is respectively connected to the two hoisting mechanisms through the transmission mechanism 2. Specifically, two second sprockets 23 are sleeved and installed on the output shaft of the speed reducer 42.

[0035] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the utility model claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A pipe lowering device for a well pipe, comprising a horizontally arranged base frame, two sets of horizontally oppositely arranged hoisting mechanisms are installed on both sides of the base frame, and a steel wire rope is arranged between the two sets of hoisting mechanisms, characterized in that: The two ends of the wire rope are respectively wound on two sets of winch mechanisms, and the winding directions of the wire rope on the two sets of winch mechanisms are opposite. A driving mechanism installed on the base frame and having an output shaft is also provided on the outer side of one set of winch mechanisms. The output shaft of the driving mechanism is connected to the two sets of winch mechanisms through a transmission mechanism respectively. The transmission mechanism includes a rotating shaft coaxially arranged with the winch mechanism and fixedly installed at the end of the winch mechanism. The rotating shaft is arranged parallel to the output shaft of the driving mechanism, and the two rotating shafts are located on the same side of the base frame. A first sprocket is sleeved and rotatably connected to the end of each rotating shaft away from the winch mechanism. Two second sprockets are sleeved and installed on the output shaft of the driving mechanism, which are respectively opposite to the first sprocket. The second sprocket is connected to the first sprocket by a transmission chain respectively. A plug-in piece capable of fixing the first sprocket and the rotating shaft relatively can be detachably connected.

2. A well pipe lowering device according to claim 1, characterized in that: The side of each first sprocket away from the hoisting mechanism is coaxially fixedly connected with a fixed tube sleeved on the rotating shaft, and a plug-in groove penetrating the fixed tube is opened on the inner wall of the fixed tube along the axial direction of the fixed tube, and the end of the rotating shaft away from the hoisting mechanism passes through the fixed tube and is fixedly connected with a protrusion, and the plug-in member includes a sleeve slidably sleeved on the rotating shaft and located outside the fixed tube, and a plug-in block corresponding to and matched with the plug-in groove is fixedly connected to the side of the sleeve close to the fixed tube, and a sliding groove penetrating the sleeve and the plug-in block in sequence is opened on the inner wall of the sleeve along the axial direction of the sleeve, and the protrusion is located in the sliding groove and is slidably connected to the sliding groove.

3. A well pipe lowering device according to claim 2, characterized in that: One end of the slide slot close to the first sprocket is fixedly connected to a limiting block.

4. A well pipe lowering device according to claim 1, characterized in that: A rope guide mechanism mounted on a base frame is arranged on the inner side of each set of hoisting mechanisms, and the rope guide mechanism includes a fixed shaft arranged parallel to the hoisting mechanism, and the fixed shaft is a circular shaft, and the two ends of the fixed shaft are respectively connected to the base frame, and a rope guide wheel with a rope guide groove is also slidably sleeved on each fixed shaft, and the two ends of the wire rope are respectively wrapped around the rope guide wheel and then wound around the hoisting mechanism.

5. A well pipe lowering device according to claim 4, characterized in that: Both ends of each fixed shaft are slidably sleeved with fixed seats, the fixed seats are fixedly connected to the base frame, and each fixed seat is threadedly connected to the fixed shaft with a fixing bolt that penetrates the fixed seat.

6. A well pipe lowering device according to claim 1, characterized in that: The driving mechanism includes a reducer and a forward and reversible driving motor, both of which are mounted on a chassis, and are transmission-connected to the driving motor and the reducer, and the output shaft of the reducer is connected to the two sets of hoisting mechanisms respectively through the transmission mechanism.

7. A well pipe lowering device according to claim 1, characterized in that: The hoisting mechanisms are all handbrake type hoists.

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