阅读说明：本技术 一种自适应平行机构的牵引装置 (Traction device of self-adaptive parallel mechanism ) 是由 吴江 舒富君 于 2019-10-31 设计创作，主要内容包括：本发明公开了一种自适应平行机构的牵引装置,其中,包括可调节高度的架体；制动泵,制动泵固定安装于架体上；牵引体,牵引体可水平滑动安装于架体上并与制动泵的伸缩杆水平对应,牵引体上设有滑动孔；阻尼件、轴A,阻尼件一端固定或可以转动的安装于轴A上,轴A贯穿安装于滑动孔后两端固定于架体上,阻尼件另一端与牵引体固定连接；牵引车刹车时,载重的挂车在自身惯性的作用下,牵引体推动制动泵的伸缩杆缩入泵内,泵的液体被压出至牵引车和/或与挂车的车桥制动液压油路内,使得牵引车和/或挂车实现刹车,降低挂车惯性力,解决了牵引装置容易被压坏的问题。同时牵引环在调节状态下一直水平,保证挂车所传至牵引环的力一直为水平方向。(The invention discloses a traction device of a self-adaptive parallel mechanism, which comprises a frame body with adjustable height; the brake pump is fixedly arranged on the frame body; the traction body can be horizontally and slidably arranged on the frame body and horizontally corresponds to the telescopic rod of the brake pump, and a sliding hole is formed in the traction body; one end of the damping piece is fixedly or rotatably arranged on the shaft A, the shaft A penetrates through the sliding hole and then is fixed on the frame body at the two ends, and the other end of the damping piece is fixedly connected with the traction body; when the tractor brakes, the loaded trailer pushes the telescopic rod of the brake pump to retract into the pump under the action of self inertia, and liquid of the pump is pressed out to the tractor and/or the axle brake hydraulic oil circuit of the trailer, so that the tractor and/or the trailer realize braking, the inertia force of the trailer is reduced, and the problem that the traction device is easily damaged by pressure is solved. Meanwhile, the traction ring is always horizontal in an adjusting state, and the force transmitted to the traction ring by the trailer is always in the horizontal direction.)

1. The traction device of the self-adaptive parallel mechanism is characterized by comprising a frame body (1) with adjustable height;

the brake pump (2), the brake pump (2) is fixedly arranged on the frame body (1);

the traction body (3) can be horizontally and slidably arranged on the frame body (1) and horizontally corresponds to the telescopic rod of the brake pump (2), and a sliding hole (31) is formed in the traction body (3);

damping piece (4), axle A (5), damping piece (4) one end is fixed or can be pivoted install on axle A (5), and axle A (5) run through to be installed on sliding hole (31) back both ends are fixed in support body (1), and damping piece (4) other end and traction body (3) fixed connection.

2. The adaptive parallel mechanism pulling apparatus as defined in claim 1, wherein: the bottom of one end of the traction body (3) is horizontally and fixedly connected with a traction ring.

3. A traction apparatus of an adaptive parallel mechanism according to claim 1 or 2, wherein: the middle of the traction body (3) is provided with a groove, the damping piece (4) is located inside the groove, one end of the damping piece (4) is fixedly connected with the shaft A (5) in the groove, and the other end of the damping piece (4) is fixedly installed at the sealing end of the groove.

4. The adaptive parallel mechanism pulling apparatus as defined in claim 1, wherein: the frame body (1) comprises a sleeve seat (11);

the end face fluted disc A (12), the end face fluted disc B (13) and the pull arm plate (14) are arranged on the two ends of the sleeve seat (11), the shaft A (5) is a step single-head threaded shaft, the end face fluted disc A (12), the end face fluted disc B (13) and the pull arm plate (14) are respectively sleeved on the two ends of the shaft A (5) which penetrate through the sleeve seat (11), and the end face fluted disc A (12) is attached to the end face fluted disc B (13);

a trailing beam (15);

the end face fluted discs are arranged on the two ends of the traction beam (15), the end face fluted discs (C17) are arranged on the two ends of the traction beam (15), the end face fluted discs (D18) are arranged on the two ends of the traction beam, and the arm pulling plate (14) is arranged on the two ends of the traction beam;

at least two fixed handles A (19), two fixed handles A (19) are fixed with axle A (5), axle B (16) screw thread end spiral closure respectively.

5. The adaptive parallel mechanism pulling apparatus as defined in claim 4, wherein: the end face fluted disc A (12) is welded with the sleeve seat (11), and the end face fluted disc B (13) is welded with one end of the pull arm plate (14); the end face fluted disc C (17) is welded with the other end of the pull arm plate (14), and the end face fluted disc D (18) is welded with the traction beam (15).

6. The adaptive parallel mechanism traction device according to claim 1 or 4, characterized in that: the bottom of the two ends of the frame body (1) is hinged with a connecting rod (6).

7. The adaptive parallel mechanism pulling apparatus as defined in claim 4, wherein: still include emergency brake (7), cover seat (11) top surface is equipped with through-hole (111), is equipped with breach (32) on traction body (3) top surface, and emergency brake (7) one end and push pedal (21) contact, and emergency brake (7) other end runs through in breach (32), through-hole (111) and outwards stretches out in proper order, and emergency brake (7) middle part is articulated with cover seat (11) top surface inner face.

8. The adaptive parallel mechanism pulling apparatus as defined in claim 7, wherein: the contact end of the emergency brake (7) and the push plate (21) is in a hook shape.

9. The adaptive parallel mechanism pulling apparatus as defined in claim 4, wherein: the guide plate (112) is fixed at the bottom of the sleeve seat (11), and the guide block (33) is fixedly arranged on the guide plate (112).

10. The adaptive parallel mechanism pulling device according to claim 9, wherein: the traction device also comprises a limiting block (34), and the limiting block (34) is fixed on the outer side of the traction body (3).

Technical Field

The invention belongs to the technical field of trailer hitching devices, and relates to a traction device of a self-adaptive parallel mechanism.

Background

The trailer is a carriage for loading goods, a traction power source is not arranged, the tractor is a power source for drawing the trailer, the load-carrying logistics are convenient to transport, the trailer and the tractor are often connected through a traction device, the heights of most trailer chassis and the tractor chassis providing traction are different, in the trailer chassis traction height adjusting device disclosed in Chinese patent publication No. CN201264651, when the double-sided fluted disc clamping device is loosened, the height between a left pull arm, a right pull arm and a tractor head is adjusted, although the connection of the trailer chassis and the tractor chassis at different heights is realized, because the actual load weight of the trailer is very large, when the presently disclosed trailer chassis traction height adjusting device is used, when the tractor is braked in time, the device can not control the great inertia force of the trailer, the device can often bear two opposite inertia forces between the trailer and the tractor, causing the draft gear to crush.

Disclosure of Invention

In order to solve the technical problem, the invention provides a traction device of a self-adaptive parallel mechanism.

The invention is realized by the following technical scheme.

The invention provides a traction device of a self-adaptive parallel mechanism, which comprises a frame body with adjustable height;

the brake pump is fixedly arranged on the frame body;

the traction body can be horizontally and slidably arranged on the frame body and horizontally corresponds to the telescopic rod of the brake pump, and a sliding hole is formed in the traction body;

damping piece, axle A, damping piece one end is fixed or can the pivoted install on axle A, and axle A runs through to install on the support body is fixed in both ends behind the sliding hole, damping piece other end and traction body fixed connection.

The beneficial effects are that when the tractor moving forwards brakes, the loaded trailer moves leftwards firstly under the action of self inertia until the rightmost side of the sliding hole is contacted with the shaft A, at the moment, the tractor is contacted with the end face of the telescopic rod of the brake pump, when the tractor is continuously pressed by the trailer, the tractor pushes the telescopic rod of the brake pump to retract into the pump, and liquid of the pump is pressed out to the tractor and/or the axle brake hydraulic oil circuit of the trailer, so that the tractor and/or the trailer realize braking, the inertia force of the trailer is reduced, and the problem that the traction device is easily damaged by pressing is solved.

Preferably, the bottom of one end of the traction body is horizontally and fixedly connected with a traction ring, and the traction ring is always horizontal in an adjusting state, so that the direction of the traction ring transmitted by the trailer is always in the horizontal direction.

Preferably, the middle part of the traction body is provided with a groove, the damping piece is positioned inside the groove, one end of the damping piece is fixedly connected with the shaft A in the groove, and the other end of the damping piece is fixedly arranged at the sealing end of the groove.

The frame body comprises a sleeve seat;

the shaft A penetrates through two ends of the sleeve seat and is respectively sleeved with the end face fluted disc A, the end face fluted disc B and the pull arm plate, and the end face fluted disc A is attached to the end face fluted disc B;

a trailing beam;

the shaft B is a single-end step threaded shaft and is arranged on the end face fluted discs C and the end face fluted discs D at two ends of the traction beam in a penetrating mode and a pull arm plate;

at least two fixed handles A, two fixed handles A close fixedly with axle A, axle B screw thread end soon respectively.

Preferably, the end face fluted disc A is welded with the sleeve seat, and the end face fluted disc B is welded with one end of the pull arm plate; and the end face fluted disc C is welded with the other end of the draw arm plate, and the end face fluted disc D is welded with the traction beam.

Preferably, the sleeve seats at the two ends of the frame body and the bottom of the traction beam are hinged with connecting rods.

The emergency brake is characterized by further comprising an emergency brake, a through hole is formed in the top surface of the sleeve seat, a notch is formed in the top surface of the traction body, one end of the emergency brake is in contact with the push plate, the other end of the emergency brake sequentially penetrates through the notch and the through hole and extends outwards, and the middle of the emergency brake is hinged to the inner face of the top surface of the sleeve seat.

Preferably, the contact end of the emergency brake and the push plate is in a hook shape.

The guide plate is fixed at the bottom of the sleeve seat, and the guide block is fixedly arranged on the guide plate.

The traction device further comprises a limiting block, and the limiting block is fixed on the outer side of the traction body.

The invention has the beneficial effects that: the hydraulic output port of the brake pump 2 is connected with a brake hydraulic oil circuit of an axle of a tractor and/or a trailer, a traction beam 15 is fixedly connected with a chassis of the tractor, a horizontal traction ring on the traction body 3 is hung with a hook of the trailer, two fixed handles A are unscrewed, so that the two fixed handles A are respectively in a screwing state to a loosening state with a shaft A and/or a shaft B, an end face fluted disc A and an end face fluted disc B are in a meshing state to a separating state, and/or an end face fluted disc C and an end face fluted disc D are in a meshing state to a separating state, the traction body rotates on the shaft A and/or the traction beam rotates on the shaft B, the height adjustment of the chassis of the trailer and the chassis of the tractor at different heights is completed, and after the height adjustment is completed, the two fixed handles A are screwed and locked with the shaft A and/or the.

When the tractor that is in forward motion is braked, the trailer of load is under self inertial effect, the horizontal pull ring bears the power that comes from the trailer horizontal direction, the traction body moves left earlier until the rightmost side of slide opening contacts with axle A, the telescopic link terminal surface contact of traction body and brake pump this moment, when the traction body continues to be pressed by the trailer, the traction body promotes the telescopic link retraction pump of brake pump in, the liquid of pump is pressed out to the tractor and/or in with the axle brake fluid pressure oil circuit of trailer, make tractor and/or trailer realize the brake, reduce trailer inertial force, the problem of draw gear by the damage easily has been solved.

Drawings

FIG. 1 is a schematic sectional front view 1 of the present invention;

FIG. 2 is a schematic structural view of the present invention;

FIG. 3 is a schematic top view of the present invention;

FIG. 4 is a schematic front view of the present invention;

FIG. 5 is a cross-sectional view taken along line A-A of FIG. 4;

FIG. 6 is a schematic sectional front view of the present invention FIG. 2;

fig. 7 is a front sectional view of the present invention, schematically illustrated in fig. 3.

In the figure: 1-a frame body; 11-a sleeve seat; 12-end face fluted disc A; 13-end face fluted disc B; 14-arm pulling plate; 15-a draft sill; 16-axis B; 17-end face fluted disc C; 18-end face fluted disc D; 19-fixed handle a; 2-a brake pump; 21-a push plate; 22-a fixed seat; 3-a traction body; 31-a sliding hole; 32-notch; 33-a guide block; 34-a limiting block; 4-a damping member; 5-axis A; 6-connecting rod; 7-an emergency brake; 111-a via; 112-guide plate.

Detailed Description

The technical solution of the present invention is further described below, but the scope of the claimed invention is not limited to the described.

See fig. 1-7.

The invention discloses a traction device of a self-adaptive parallel mechanism, which comprises a height-adjustable frame body 1; the brake pump 2, the pump body seat of the brake pump 2 is fixedly arranged on the frame body 1 by using a plug component for example; the traction body 3 can be horizontally and slidably arranged on the frame body 1 and horizontally corresponds to the telescopic rod of the brake pump 2; be equipped with slide opening 31 on the traction body 3, damping piece 4, axle A5, damping piece 4 one end is fixed or can be pivoted install on axle A5, and axle A5 runs through to be installed on both ends are fixed in support body 1 behind slide opening 31, the damping piece 4 other end and traction body 3 fixed connection.

In order to reduce the production cost, the damping member 4 has damping characteristics, and the damping member 4 may be a forulidi shock absorber, a gas spring, or a coil spring.

The brake pump 2 may use the brake of the force corporation RT 3010098T.

When the tractor is used, a hydraulic output port of the brake pump 2 is connected with a tractor and/or an axle brake hydraulic oil circuit of a trailer, the height-adjustable frame body 1 is fixedly connected with a tractor chassis, the frame body 1 is adjusted, so that the traction body 3 is fixedly connected with the trailer chassis with a height difference with the tractor chassis, under the pulling of the shaft A5, the traction body 3 moves rightwards, the leftmost inner surface of the sliding hole 31 is contacted with the shaft A5, the tractor pulls the trailer, the transmission of the pulling force between the trailer chassis and the tractor chassis at different heights is realized, and at the moment, the end surface of the traction body 3 is separated from the end surface of the telescopic rod of the brake pump 2 at intervals;

when the traction body 3 is required to be separated from the trailer, the tractor backs up, the frame body 1 moves rightwards relative to the traction body 3, the shaft A5 is in a contact state with the sliding hole 31 to a separation state, and the traction body 3 and the end face of the telescopic rod of the brake pump 2 are in a spaced separation state at the moment, so that hydraulic oil of the brake pump 2 cannot flow into the tractor and/or an axle brake hydraulic oil path of the trailer from the pump body, and the trailer is separated from the traction body 3 at the moment;

when the tractor in forward motion is braked, the loaded trailer moves leftwards firstly until the rightmost side of the sliding hole 31 is contacted with the shaft A5 under the action of self inertia, at the moment, the tractor 3 is contacted with the end face of the telescopic rod of the brake pump 2, when the tractor 3 is continuously pressed by the trailer, the tractor 3 pushes the telescopic rod of the brake pump 2 to retract into the pump, the liquid of the pump is pressed out to the tractor and/or the axle brake hydraulic oil circuit of the trailer, so that the tractor and/or the trailer realize braking, the inertia force of the trailer is reduced, and the problem that the traction device is easily damaged by pressing is solved.

The traction ring integrated with the traction body 3 is fixed at one end, so that the hook of the trailer can be conveniently hung and buckled.

Traction ring fixed connection is less than the traction body 3 body in the bottom of the traction body 3 in the vertical direction of traction ring for reduce trailer chassis and the difference in height who draws the vehicle chassis, improve the fastness of the 3 power transmission of the traction body simultaneously.

The middle part of the traction body 3 is provided with a hollow groove, the damping part 4 is positioned in the groove of the traction body 3, one end of the damping part 4 is fixedly connected with a shaft A5 penetrating the hollow part of the traction body 3 and close to the brake pump 2, and the other end of the damping part 4 is installed on a rod body penetrating through the other end of the traction body 3 and fixedly installed in the traction body.

The tail end of the telescopic rod of the brake pump 2 is provided with a push plate 21, and the outer contour of the push plate 21 is larger than the outer edge of the groove arranged on the traction body 3 and corresponds to the outer edge of the groove.

The height-adjustable function of the frame body 1 is realized, the frame body 1 comprises a sleeve seat 11, a through hole is formed in the sleeve seat 11, a shaft A5 is a step single-head threaded shaft, and a threaded end of a shaft A5 is arranged in the through hole of the sleeve seat 11 in a penetrating mode;

at least two end face fluted discs A12, wherein the two end face fluted discs A12 are respectively fixed on two sides of the sleeve seat 11 in a concentric way, for example, by welding, with the tooth surfaces facing outwards;

the two end face fluted discs B13 and the two pull arm plates 14 are respectively fixedly connected with the two pull arm plates 14 in a welding way and are respectively concentrically meshed with the two end face fluted discs A12, and the two pull arm plates 14 are respectively provided with through holes which are respectively sleeved on the shaft A5;

the traction beam 15 is provided with a through hole;

the shaft B16 and the shaft B16 are single-head step threaded shafts, and the threaded end of the shaft B16 is arranged in a through hole of the draft sill 15 and a through hole at the other end of the two draw arm plates 14 in a penetrating way;

the two end face fluted discs C17 and the two end face fluted discs C17 can be respectively welded and fixed at the other ends of the two pull arm plates 14;

at least two end face fluted discs D18 and two end face fluted discs D18 can be respectively welded and fixed on two outer side surfaces of the traction beam 15 and are respectively correspondingly meshed with the two end face fluted discs C17;

at least two fixed handles A19, two fixed handles A19 are screwed and fixed with the threaded ends of the shaft A5 and the shaft B16 respectively.

The traction body 3 is arranged on the inner side of the bottom of the sleeve seat 11, one end of the damping part 4 is sleeved on a shaft A5 on the inner side of the bottom of the sleeve seat 11, and the brake pump 2 is fixed on a fixed seat 22 fixed on the inner side of the bottom of the sleeve seat 11.

After the installation is finished, the outer side surfaces of one ends of the two pull arm plates 14 are respectively contacted with the inner surface between the step end of the shaft A5 and a fixed handle A19, and the fixed handle A15 and the step end of the shaft A5 are fixedly locked with each other; the outer side surfaces of the other ends of the two pull arm plates 14 are respectively contacted with the inner surfaces between the step end of the shaft B16 and the other fixing handle A19, and the fixing handle A15 and the step end of the shaft B16 are fixedly locked between the inner surfaces.

When the tractor is used, the two fixing handles A19 and the shaft A5 and/or the shaft B16 are unscrewed, so that the end-face toothed disc A12 and the end-face toothed disc B13 are in a meshing state to a separation state, and/or the end-face toothed disc C17 and the end-face toothed disc D18 are in a meshing state to a separation state, the traction body 3 rotates on the shaft A5 and/or the traction beam 15 rotates on the shaft B16, and the trailer chassis and the tractor chassis which are located at different heights are matched and fixedly connected with the traction body 3 and the traction beam 15 respectively; after the connection is completed, the two fixing handles A19 are screwed and locked with the shaft A5 and/or the shaft B16.

The two fixing handles A19 are opposite to the screwing directions of the threaded ends of the shaft A5 and the shaft B16 respectively, and when the two ends of the two pull arm plates 14 apply force to the axial directions of the shaft A5 and the shaft B16, the two fixing handles A19, the shaft A5 and the shaft B16 form self-locking force, so that the screwing locking force is improved, and the stability is improved.

Through holes are formed in the centers of the end-face toothed disc A12 and the end-face toothed disc B13, the shaft A5 concentrically penetrates through the through holes which are arranged on the end-face toothed disc A12 and the end-face toothed disc B13 at intervals, the situation that torque can be generated in a locking state due to the fact that the end-face toothed disc A12, the end-face toothed disc B13 and the shaft A5 are arranged eccentrically is avoided, and the stress stability of the sleeve base 11 and the arm pulling plate 14 in the locking state is improved.

Through holes are formed in the centers of the end face toothed disc C17 and the end face toothed disc D18, the shaft B16 penetrates through the through holes of the end face toothed disc C17 and the end face toothed disc D18 at a concentric interval, the situation that torque can be generated in a locking state due to the fact that the shaft B16, the end face toothed disc C17 and the end face toothed disc D18 are installed in a non-concentric mode is avoided, and the stress stability of the draw arm plate 14 and the draw beam 15 in the locking state is improved.

The sleeve seats 11 at the two ends of the frame body 1 and the bottom of the traction beam 15 are hinged with connecting rods 6.

The two ends of the connecting rod 6 are sleeves, the sleeves at the two ends of the connecting rod 6 are positioned on two sides of the bottom of the sleeve seat 11 and the bottom of the traction beam 15, one stud bolt sequentially penetrates through holes on two sides of the sleeve seat 11 and the sleeve at one end of the connecting rod 6 and is screwed by nuts, and the other stud bolt sequentially penetrates through holes on two sides of the traction beam 15 and the sleeve at the other end of the connecting rod 6 and is screwed by nuts.

Still include emergency brake 7, the top surface of cover seat 11 is equipped with through-hole 111, is equipped with breach 32 on the top surface of traction body 3 and the contact of 2 telescopic links of brake pump, and emergency brake 7 one end and push pedal 21 contact, and the emergency brake 7 other end runs through in breach 32, through-hole 111 and outwards stretches out in proper order, and emergency brake 7 middle part is articulated with the top surface inner face of cover seat 11.

During the use, the one end that emergency brake 7 leaks outward with steel wire or act as go-between fixed connection, emergency brake 7 is under emergency to in pushing the pump body 2 with the 2 telescopic links of brake pump with 11 pin joints rotations of cover seat, brake trailer and/or tractor, improve equipment's security.

The contact end of the emergency brake 7 and the push plate 21 is in a hook shape, the outer extension edges of the emergency brake 7 and the push plate 21 are taken as fulcrums, and the hook head rotates to push the push plate 21 more quickly and powerfully.

A guide plate 112, wherein the guide plate 112 is horizontally fixed at the bottom of the sleeve seat 11 by welding, for example, so that the sleeve seat 11 and the guide plate 112 form a hollow slideway;

the guide block 33, the guide block 33 is fixedly installed on the guide plate 112, so that the traction body 3 is more stable under the guidance of the guide block 33.

The stopper 34, stopper 34 fixed suit is around the body 3 outside on the left of guide block 33 for when the body 3 is moving to the left, the stopper 34 forms spacingly with emergency brake 7 contact back, makes when the body 3 is moving to the right, the stopper 34 forms spacingly with the guide block 33 contact back, improves the controllability of the body 3 motion of pulling.

The working principle is as follows: connecting a hydraulic output port of a brake pump 2 with a brake hydraulic oil circuit of an axle of a tractor and/or a trailer, fixedly connecting a traction beam 15 with a chassis of the tractor, hanging and buckling a traction ring on a traction body 3 with a hook of the trailer, unscrewing two fixed handles A19, enabling two fixed handles A19 to be respectively in a screwing state and a loosening state with a shaft A5 and/or a shaft B16, enabling an end-face fluted disc A12 and an end-face fluted disc B13 to be in a meshing state and a separating state, and/or enabling an end-face fluted disc C17 and an end-face fluted disc D18 to be in a meshing state and a separating state, rotating the traction body 3 on the shaft A5 and/or rotating the traction beam 15 on the shaft B16, completing height adjustment of the chassis of the tractor and the chassis at different heights, and after the height adjustment, screwing and locking the two fixed handles A19 with the shaft A5 and/or the shaft B16; at this time, the leftmost inner surface of the sliding hole 31 is in contact with the shaft A5, and the end surface of the traction body 3 is not in contact with the end surface of the telescopic rod of the brake pump 2, so that the traction ring is kept horizontal in an adjusting state.

When the traction body 3 is required to be separated from the trailer, the tractor backs up, the trailer is in a static and stable state at the moment, and the shaft A5 fixed on the frame body 1 is positioned in the middle of the sliding hole 31 and is not in contact with the left side and the right side of the sliding hole 31 because the traction body 3 is fixedly hung with a hook of the trailer. At this time, the end face of the traction body 3 and the end face of the telescopic rod of the brake pump 2 are in a spaced separation state. So that the hydraulic oil of the brake pump 2 can not flow into the tractor and/or the axle brake hydraulic oil circuit of the trailer from the pump body, and the trailer is separated from the traction ring on the traction body 3 at the moment.

When the tractor in forward motion is braked, the loaded trailer bears the force from the horizontal direction of the trailer under the action of self inertia, the traction body 3 moves leftwards firstly until the rightmost side of the sliding hole 31 is contacted with the shaft A5, at the moment, the traction body 3 is contacted with the end face of the telescopic rod of the brake pump 2, when the traction body 3 is continuously pressed by the trailer, the traction body 3 pushes the telescopic rod of the brake pump 2 to retract into the pump, the liquid of the pump is pressed out to the tractor and/or the axle brake hydraulic oil circuit of the trailer, so that the tractor and/or the trailer realize braking, the inertia force of the trailer is reduced, and the problem that the traction device is easily damaged by pressing is solved. The traction body 3 is reset by the damping piece 4 moving to the right.

When the trailer is used, the damping part 4 is selected, and the ratio of the weight of the trailer to the force in the maximum compression state is 1: 0.3, the weight of the trailer is in tons and the force in the maximum compression state is in kilonewtons. For example, when the trailer weighs 1T, the force with which the damper 4 compresses to the maximum state is 3000N.