JP5318794B2 - Trailer axle lifting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform an operation for measuring the overall weight of a vehicle connected to a trailer by an existing measuring stand irrespective of the number of axles of the trailer, and also secure the safety of the trailer during the traveling. <P>SOLUTION: A solenoid valve 56 is installed in a pneumatic pressure circuit 55 for connecting an actuator 48 driving a lifting traveling axle between the ground-contact position and the retreated position to a pneumatic pressure tank 54. A solenoid valve 58 is installed in a pneumatic pressure circuit 57 for connecting pneumatic springs 44 installed on suspensions for supporting the lifting traveling axle to the pneumatic pressure tank 54. The solenoid valves 56, 58 are switched by an operation switch 62 for opening and closing an electric circuit 63 to operate the driving of the lifting traveling axle. The axle lifting device further includes a relay 66 for opening and closing the electric circuit 63 by a signal from a parking brake sensor 69. When the stop state of the vehicle of the trailer is not detected by the parking brake sensor 69, the driving of the lifting traveling axle to the retreated position is cut off, and the lifting traveling axle is moved to the ground-contact position. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a trailer axle lifting device that drives a lift-type traveling axle provided with traveling wheels to a grounding position where the traveling wheels contact a road surface and a retracted position where the traveling wheels are separated from the road surface.

  Cargoes that can be transported by large trucks are limited in weight and length, and a tractor-trailer coupled vehicle is used when transporting cargo that exceeds the limit weights or dimensions. This coupled vehicle includes a full trailer type in which a cargo bed is provided on a tractor and a trailer, and a semi-trailer type in which a cargo bed is provided only on a trailer. The trailer as a towed vehicle is not provided with drive wheels, and the trailer is driven by a tractor as a towed vehicle and follows.

  In such a freight vehicle, the axle load applied to each axle is regulated by laws and the like, and traveling in a state where the axle weight exceeds the limit load is prohibited. Therefore, a large trailer is provided with a plurality of traveling axles each provided with traveling wheels, and the trailer is loaded with the maximum weight of cargo by supporting the vehicle by the plurality of traveling axles. Thus, the axle load applied to each traveling axle can be accommodated within the limit load. However, when the trailer travels when no cargo is loaded on the trailer or when the weight of the cargo is small, traveling with all the traveling wheels in contact with the ground causes deterioration of tractor fuel consumption and wheel wear. .

  Therefore, in Patent Document 1, a traveling axle arranged on the rear side of the vehicle among a plurality of traveling axles provided on the trailer is a lifting type, and a lifting type traveling axle is provided according to the weight of cargo loaded on the trailer. A trailer axle lifting device that is driven up and down is described. As a result, when traveling with no cargo loaded on the trailer, it is possible to travel with the traveling wheels provided on the liftable traveling axle away from the road surface, improving the fuel efficiency of the tractor. Reduction of wheel wear can be achieved.

  Patent Document 2 discloses a parking brake device for applying a braking force to a traveling wheel of a trailer when the trailer is parked. The parking brake device has a structure that applies braking force to the traveling wheel by a coil spring by exhausting compressed air in the spring brake chamber, and a pressure sensor is incorporated in the pneumatic circuit that connects the spring brake chamber and the pneumatic tank It is. A parking brake sensor comprising this pressure sensor can detect whether or not the trailer parking brake is operating.

JP 2002-205524 A JP 2009-107396 A

  By the way, when measuring the weight of the cargo loaded on the trailer, the total weight of the vehicle is measured by placing the tractor and trailer on the measuring table with the cargo loaded, and the tractor and trailer are measured from the total weight of the vehicle. The weight of the cargo is measured by subtracting the weight of only the vehicle. Conventionally, a trailer generally has two traveling axles on the rear side of the vehicle, and a measurement table is formed corresponding to the two-axis trailer. In other words, the length of the existing measuring table is slightly longer than the length from the front wheel of the tractor to the last wheel of the biaxial trailer.

  However, in recent years, a three-axis trailer that can load more cargo has become widespread in order to improve transport efficiency, and this three-axis trailer is mounted on an existing measuring table that supports a two-axis trailer. Can not be placed. That is, in the three-axis trailer, the length from the front wheel of the tractor to the last wheel of the three-axis trailer is longer than the length of the existing measuring table, and the last wheel of the trailer protrudes from the measuring table. Therefore, when a three-axis trailer is used, the total vehicle weight of the connected vehicle cannot be measured at a time using an existing measuring table, and the work of measuring the weight of the cargo becomes complicated.

  Therefore, it is conceivable that the tractor and the three-axis trailer can be mounted on an existing measurement table by driving the rear wheel of the three-axis trailer up by an axle lifting device as described in Patent Document 1. . However, the conventional axle lifting device is intended to improve tractor fuel efficiency and reduce wheel wear during traveling, and controls the vertical driving of the lifting axle according to the weight of the cargo loaded on the trailer. Like to do. Therefore, when the weight of the cargo is large and the trailer cannot travel on two axes, the liftable traveling axle provided with the last wheel of the three-axis trailer cannot be driven up, and the last wheel of the trailer does not exist. It remains protruding from the measurement table, and the above problem cannot be solved. On the other hand, even when the weight of the cargo is large and the trailer cannot travel in two axes, it is possible to make the structure so that the liftable traveling axle can be lifted. In that case, the last wheel of the three-axis trailer can be lifted from the road surface. This is a safety issue because there is a risk of traveling in a separated state.

  An object of the present invention is to easily perform the operation of measuring the total vehicle weight of a connected vehicle using an existing measuring table regardless of the number of trailer axes, and to ensure safety during traveling.

  The trailer axle lifting device according to the present invention is provided on a trailer that runs by being pulled by a tractor provided with front wheels and rear wheels, and is disposed on the vehicle rear side among a plurality of running axles provided with running wheels. A trailer axle lifting device coupled to at least one lifting and lowering traveling axle for driving the lifting and lowering traveling axle to a grounding position where the traveling wheel contacts the road surface and a retracted position where the traveling wheel separates from the road surface. An actuator that moves forward and backward by fluid pressure to drive the liftable traveling axle to the ground position and the retracted position, and a fluid pressure circuit that connects the actuator and a fluid pressure source, A first control valve that is switched between a position for supplying fluid to the actuator and a position for discharging fluid in the actuator; and turning off the first control valve. An operation switch for operating the vehicle, vehicle stop detection means for detecting whether or not the trailer is in a vehicle stop state, and when the trailer is not detected in the vehicle stop state by the vehicle stop detection means, Control means for blocking the drive of the liftable traveling axle to the retracted position and setting the liftable traveling axle to the grounding position, and placing the tractor and the trailer on a measurement table When measuring the total vehicle weight, the distance from the front wheel of the tractor is longer than the length of the measurement table, and the total vehicle weight is measured by driving the liftable traveling axle protruding from the measurement table to the retracted position. It is possible to make it possible.

  The trailer axle lifting device according to the present invention is provided in a fluid pressure circuit that connects a suspension mounted on the lifting traveling axle and a fluid pressure source so that the lifting traveling axle is in the grounding position. When the operation switch is operated, the fluid in the suspension is discharged when the operation switch is operated so that the fluid is supplied to the suspension when the operation switch is operated and the liftable traveling axle is in the retracted position. A second control valve that is switched to a discharge position to be discharged, and a state in which it is not detected by the vehicle detection means that the trailer is in a vehicle stop state, to the discharge position of the second control valve. And the control means for blocking the switching and setting the elevating traveling axle to the grounding position.

  The trailer axle lifting apparatus according to the present invention is characterized in that the vehicle stop detection means is a parking brake sensor that detects whether or not a parking brake that applies a braking force to the traveling wheels is operating.

  The trailer axle lifting apparatus according to the present invention is characterized in that the vehicle stop detection means is a vehicle speed sensor for detecting a vehicle speed of the trailer.

  The trailer axle lifting device according to the present invention is characterized in that the operation switch for opening and closing an electric circuit connecting the control valve formed of an electromagnetic valve and a power source is provided.

  The trailer axle lifting apparatus according to the present invention is characterized in that a relay switch is provided as the control means for opening and closing the electric circuit in response to a signal from the vehicle stop detection means.

  According to the present invention, since at least one traveling axle disposed on the rear side of the vehicle among the plurality of traveling axles of the trailer is liftable, the liftable traveling axle is lifted to the retracted position to drive the road surface. The inter-axis distance between the foremost wheel and the last wheel of the grounded connected vehicle is shortened. As a result, even if the distance between the front wheel of the tractor and the last wheel of the trailer is longer than the length of the existing measuring table, and the trailer's traveling wheel protrudes from the measuring table, the liftable traveling axle is raised to the retracted position. By driving, the tractor and trailer can be placed on the measuring table, and the total vehicle weight of the connected vehicle can be easily measured by the measuring table. In this trailer, when it is not detected by the vehicle stop detection means that the trailer is in a vehicle stopped state, the drive to the retracted position of the liftable traveling axle is cut off and the liftable traveling axle is set to the grounding position. Since the means is provided, it is possible to prevent the elevating-type traveling axle from traveling in a state where it is driven to the retracted position, and to ensure safety during traveling.

It is a side view which shows the trailer provided with the axle raising / lowering apparatus of this invention. It is a side view which shows the suspension which supports the travel axle of a trailer. It is the schematic which shows the control circuit of an axle raising / lowering apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a coupled vehicle of a tractor 11 and a trailer 12, and this coupled vehicle is a semi-trailer type in which only a trailer 12 is provided with a loading platform. The tractor 11 has tractor axles 13 and 14, and left and right front wheels 15 and rear wheels 16 are provided at both ends of the tractor axles 13 and 14, respectively. The output shaft of the engine mounted on the tractor 11 is connected to the tractor axle 14 through a power transmission mechanism, and the tractor 11 travels by pulling the trailer 12 with the rear wheels 16 as drive wheels.

  The trailer 12 includes a chassis frame (trailer main body) 17 extending in the vehicle front-rear direction, and includes three traveling axles 18 to 20 at the vehicle rear portion of the chassis frame 17. Left and right traveling wheels 21 to 23 are provided at both ends of the traveling axles 18 to 20, respectively. Further, the trailer 12 is connected to the coupler 25 of the tractor 11 by a king pin 24 provided at the front portion of the chassis frame 17 and is driven by the traveling wheels 21 to 23 by being pulled by the tractor 11. Yes. In this trailer 12, a tank body 26 is formed integrally with the chassis frame 17 for loading powder particles such as quick lime and resin pallets as cargo.

  Of the three traveling axles 18 to 20 provided on the trailer 12, the traveling axle 20 disposed at the rear of the vehicle is a liftable type, and the other traveling axles 18 and 19 are not liftable. The traveling axles 18 to 20 are supported by suspensions provided on the left and right sides of the chassis frame 17.

  FIG. 2 is a side view showing a suspension that supports the traveling axle of the trailer, and shows a suspension that is provided on the left side of the chassis frame 17 in the traveling direction and supports the traveling axles 18 to 20. The suspension 31 that supports the non-lifting traveling axles 18 and 19 includes a leaf spring 33 to which a bearing box 32 that supports the traveling axles 18 and 19 is attached, respectively, and one end of the leaf spring 33 and the chassis frame 17. In between, an air spring 34 is mounted. A bracket 35 is fixed to the chassis frame 17, and the other end of the leaf spring 33 is connected to the bracket 35 so as to be swingable around the bracket 35. A shock absorber 36 is mounted between the bracket 35 and the bearing box 32. A similar suspension 31 is provided on the right side of the chassis frame 18 in the traveling direction.

  The suspension 41 that supports the elevating traveling axle 20 has a leaf spring 43 to which a bearing box 42 that supports the traveling axle 20 is attached. Between the one end of the leaf spring 43 and the chassis frame 18, there is no air. A spring 44 is mounted. A bracket 45 is fixed to the chassis frame 17, and the other end of the leaf spring 43 is connected to the bracket 45 so as to be movable in the vertical direction, unlike the leaf spring 33 of the suspension 31. A shock absorber 46 is mounted between the bracket 45 and the bearing box 42.

  An actuator 48 is attached to an attachment plate 47 provided on the bracket 45. The actuator 48 has a push rod 49 that moves forward and backward by air pressure, and is a type that drives the push rod 49 by air pressure. The actuator 48 is of a type in which a diaphragm that is elastically deformed by air pressure is incorporated, and a push rod 49 is attached to the diaphragm. The actuator 48 is not limited to this type, and a type in which a piston that reciprocates in the axial direction by air pressure is incorporated therein and the push rod 49 is driven by the piston can be used.

  A drive member 50 is connected to the push rod 49, and the drive member 50 is engaged with the other end of the leaf spring 43. Therefore, when compressed air is supplied to the actuator 48 and the compressed air in the air spring 44 is discharged to the outside, the other end portion of the leaf spring 43 is lifted by the push rod 49 via the drive member 50, so that the elevator travels. The axle 20 is driven up to the retracted position. As a result, the traveling wheels 23 provided on the traveling axle 20 are located away from the road surface R. In FIG.1 and FIG.2, the state which the traveling wheel 23 separated from the road surface R is shown. On the other hand, when the compressed air in the actuator 48 is discharged to the outside and the compressed air is supplied to the air spring 44, the elevating traveling axle 20 is driven down to the grounding position. As a result, the traveling wheel 23 comes into contact with the road surface R in the same manner as the traveling wheels 21 and 22.

  As shown in FIG. 1, when the traveling wheel 23 is separated from the road surface R, the inter-axis distance between the front and rear wheels of the connected vehicle that contacts the road surface R, that is, the front wheel 15 of the tractor 11 The inter-axis distance between the trailer 12 and the traveling wheel 22 is L1. Further, under the state where the traveling wheel 23 is in contact with the road surface R, the inter-axis distance between the foremost wheel and the last wheel of the connected vehicle that is in contact with the road surface R, that is, the traveling wheel of the front wheel 15 of the tractor 11 and the trailer 12. The inter-axis distance with 23 is L2. In this way, the distance L1 between the axes when the elevating traveling axle 20 is driven upward and the traveling wheels 23 are separated from the road surface R is the lowering of the elevating traveling axle 20 and the traveling wheels 23 are moved to the road surface R. It becomes smaller than the inter-axis distance L2 when it is grounded. As a result, by raising and lowering the liftable traveling axle 20 to the retracted position, the existing length M is formed slightly longer than the inter-axis distance L1 so as to correspond to the biaxial trailer as shown in the figure. The connected vehicle including the tractor 11 and the three-axis trailer 12 can be placed on the measurement table 51, and the total vehicle weight of the connected vehicle can be measured by the measurement table 51.

  That is, in the state where the traveling wheel 23 is in contact with the road surface R, the inter-axis distance L2 between the front and rear wheels of the connected vehicle that is in contact with the road surface R is longer than the length M of the measuring table 51, and the road surface R The traveling wheel 23 that contacts the ground protrudes from the measurement table 51. Therefore, the total vehicle weight cannot be measured at a time by the measurement stand 51, and the operation of measuring the total vehicle weight becomes complicated. On the other hand, in a state in which the traveling wheel 23 is separated from the road surface R, the inter-axis distance L1 between the front and rear wheels of the connected vehicle that contacts the road surface R is shorter than the length M of the measuring table 51, and the tractor 11 In addition, the trailer 12 can be placed on the measurement table 51. In this way, by raising and lowering the liftable traveling axle 20 arranged on the vehicle rear side among the three traveling axles 18 to 20 of the trailer 12 to the retracted position, the length M corresponding to the two-axle trailer. The existing measuring table 51 makes it possible to easily measure the total vehicle weight of the connected vehicle including the three-axis trailer 12.

  FIG. 3 is a schematic diagram showing a control circuit of the axle lifting device. The trailer 12 is equipped with a pneumatic tank 54 for storing compressed air. The pneumatic tank 54 as a fluid pressure source is supplied with compressed air from the tractor 11 side. In order to supply compressed air to the actuators 48 attached to the left and right sides of the chassis frame 17, pneumatic circuits 55 that connect the pneumatic tanks 54 to the respective actuators 48 are provided. The pneumatic circuit 55 incorporates an electromagnetic valve 56 as a first control valve. When the electromagnetic valve 56 is switched to the open position by a signal sent to the electromagnetic valve 56, the compressed air in the pneumatic tank 54 is respectively changed. Is supplied to the actuator 48 and the push rod 49 is projected. When the solenoid valve 56 is switched to the discharge position by a signal sent to the solenoid valve 56, the communication between the pneumatic tank 54 and each actuator 48 is cut off and the compressed air in the actuator 48 is discharged to the outside.

  In order to supply compressed air to air springs 34 and 44 attached to the left and right sides of the chassis frame 17, a pneumatic circuit 57 that connects the pneumatic tank 54 and the air springs 34 and 44 is provided. . The air springs 34 provided on the non-elevating suspension 31 are directly connected to the pneumatic tank 54. The compressed air in the pneumatic tank 54 is always supplied to the air spring 34 so that the suspension 31 functions. . On the other hand, an air spring 44 provided on the liftable suspension 41 is connected to a pneumatic tank 54 via an electromagnetic valve 58 as a second control valve. When the electromagnetic valve 58 is switched to the open position by a signal sent to the electromagnetic valve 58, the compressed air in the pneumatic tank 54 is supplied to each air spring 44 and the suspension 41 functions. When the solenoid valve 58 is switched to the discharge position by a signal sent to the solenoid valve 58, the communication between the pneumatic tank 54 and each air spring 44 is cut off and the compressed air in the air spring 44 is discharged to the outside. The

  These solenoid valves 56 and 58 are connected to a power source 60 provided on the tractor 11 side via a connector 61. An operation switch 62 is provided at the driver seat of the tractor 11, and an electric circuit 63 that connects the electromagnetic valves 56 and 58 and the power source 60 is opened and closed by the operation switch 62. When the electric circuit 63 is operated to be energized by the operation switch 62, the electromagnetic valve 56 is in the open position and the electromagnetic valve 58 is in the discharge position. As a result, the elevating traveling axle 20 is driven up to the retracted position by the actuator 48, and the traveling wheels 23 are separated from the road surface R. Further, when the electric circuit 63 is operated to be cut off by the operation switch 62, the electromagnetic valve 56 is set to the discharge position and the electromagnetic valve 58 is set to the open position. As a result, the liftable traveling axle 20 is driven down to the grounding position, and the traveling wheel 23 comes to a position where it grounds the road surface R. Note that the electric circuit 63 is provided with a fuse 64 and a lamp 65, and the liftable traveling axle 20 is in the retracted position by the lamp 65 installed on the instrument panel of the driver seat of the tractor 11. It is displayed to the driver.

  This electric circuit 63 incorporates a relay 66 that opens and closes the electric circuit 63 in accordance with the traveling state of the trailer 12. The relay 66 as a control means is provided on the trailer 12 side, and has a normally-open switch unit 66a that opens and closes the electric circuit 63, and a drive unit 66b that receives the signal and drives the switch unit 66a. The drive unit 66 b is connected to the power supply 60 via a connector 67, and an amplifier (amplifier) 68 is incorporated between the drive unit 66 b and the connector 67. The trailer 12 is provided with a parking brake sensor 69 as vehicle stop detection means, and the parking brake sensor 69 is connected to an amplifier 68. As this parking brake sensor 69, for example, as described in Patent Literature 2, the parking brake is activated by detecting the pressure in the pneumatic circuit for operating the parking brake that applies braking force to the traveling wheels 21, 22. A pressure sensor is used to detect whether or not this is done.

  When the parking brake sensor 69 detects that the parking brake is operating and a signal is sent from the parking brake sensor 69 to the amplifier 68, the signal amplified by the amplifier 68 is sent to the drive unit 66b of the relay 66. The switch part 66a is closed. That is, when the parking brake sensor 69 detects that the trailer 12 is in a vehicle stop state, the operation valves 62 can be switched between the electromagnetic valves 56 and 58. As a result, the liftable traveling axle 20 can be driven up to the retracted position, and the total vehicle weight of the connected vehicle can be measured by the measuring platform 51. On the other hand, when the parking brake sensor 69 does not detect that the parking brake is operating, the relay 66 remains open, and the switching of the electromagnetic valves 56 and 58 by the operation switch 62 is interrupted. That is, when it is not detected by the parking brake sensor 69 that the trailer 12 is in the vehicle stop state, the driving of the liftable traveling axle 20 to the retracted position is interrupted, and the traveling axle 20 becomes the grounding position. As a result, when the trailer 12 travels, the liftable traveling axle 20 is forcibly driven down to the ground position, and the traveling wheel 23 is reliably prevented from traveling away from the road surface R.

  Thus, since the traveling axle 20 disposed on the rear side of the vehicle among the traveling axles 18 to 20 of the trailer 12 is liftable, the liftable traveling axle 20 is driven up to the retracted position so that the road surface R The inter-axis distance between the foremost wheel and the last wheel of the grounded connected vehicle is shortened. Thereby, even when the distance L2 between the front wheel 15 of the tractor 11 and the traveling wheel 23 of the trailer 12 is longer than the length M of the existing measuring table 51, the traveling wheel 23 protrudes from the measuring table 51. By separating 23 from the road surface R, the inter-axis distance L1 from the front wheel 15 of the tractor 11 grounded to the road surface R to the traveling wheel 22 of the trailer 12 can be made shorter than the length M of the measuring table 51. Therefore, the tractor 11 and the trailer 12 can be placed on the measurement table 51, and the total vehicle weight of the connected vehicle can be easily measured by the measurement table 51. In this trailer 12, when it is not detected by the parking brake sensor 69 that the trailer 12 is in a vehicle stop state, the ascending drive of the liftable traveling axle 20 to the retracted position is cut off, and the traveling axle 20 is set to the ground position. Since the relay 66 is provided, it is possible to prevent the traveling axle 20 from traveling while being driven to the retracted position. As a result, when the cargo is loaded on the trailer 12 and the trailer 12 cannot travel in two axes, the traveling wheel 23 is reliably prevented from traveling away from the road surface R, thus ensuring safety during traveling. can do.

  In the above-described embodiment, the parking brake sensor 69 is used as the vehicle stop detection unit that detects whether or not the trailer 12 is in a vehicle stop state. However, the present invention is not limited to this. For example, a vehicle speed sensor that detects the vehicle speed of the trailer 12 may be used as the vehicle stop detection means. In this case, control is performed to open the relay 66 at a vehicle speed of about 2 km / h or more of the trailer 12. Can be considered. As the vehicle speed sensor, the output of a speed switch provided in an ABS (anti-lock brake system) can be used.

  Moreover, in the said embodiment, although the relay 66 which opens and closes the electric circuit 63 with the signal from a vehicle stop detection means was used as a control means, it is not limited to this. For example, a control valve that opens and closes the pneumatic circuits 55 and 57 by a signal from the vehicle stop detection means may be provided as the control means.

  Furthermore, the traveling axle 19 may be liftable. In that case, the total vehicle weight of the connected vehicle can be measured by an existing measuring table having a length corresponding to a single-axis trailer. Further, the trailer 12 is not limited to three axes, and the existing structure whose length is shorter than the distance between the front wheels 15 of the tractor 11 and the last wheel of the trailer 12 is also obtained in the case of a two-axis or four-axis trailer. It is possible to easily measure the total vehicle weight of the connected vehicle using the measurement stand. That is, according to the present invention, it is possible to easily perform the measurement work of the total vehicle weight of the connected vehicle using the existing measuring table regardless of the number of the traveling axles of the trailer 12.

  Further, in the above embodiment, the elevating traveling axle 20 is driven to the retracted position by switching the electromagnetic valve 56 to the open position, but the elevating traveling is performed by switching the electromagnetic valve 56 to the discharge position. The structure of the actuator 48 that drives the axle 20 to the retracted position may be used.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the trailer 12 is not limited to a tank trailer that transports granular materials, but may be a trailer that transports other cargo. Furthermore, although the semi-trailer type connected vehicle is used in the embodiment, a full trailer type connected vehicle may be used, and the tractor shaft 14 of the tractor 11 may be two or three axes.

DESCRIPTION OF SYMBOLS 11 Tractor 12 Trailer 13, 14 Tractor axle 15 Front wheel 16 Rear wheel 17 Chassis frame 18, 19 Traveling axle (non-lifting type)
20 Traveling axle (lifting type)
21-23 Traveling wheel 24 Kingpin 25 Coupler 26 Tank body 31, 41 Suspension 32, 42 Bearing box 33, 43 Leaf spring 34, 44 Air spring 35, 45 Bracket 36, 46 Shock absorber 47 Mounting plate 48 Actuator 49 Push rod 50 Drive Member 51 Measuring table 54 Pneumatic tank 55 Pneumatic circuit 56 Solenoid valve 57 Pneumatic circuit 58 Solenoid valve 60 Power supply 61 Connector 62 Operation switch 63 Electric circuit 64 Fuse 65 Lamp 66 Relay 66a Switch part 66b Drive part 67 Connector 68 Amplifier 69 Parking brake sensor

Claims (6)

Connected to at least one liftable traveling axle disposed on the vehicle rear side among a plurality of traveling axles provided with traveling wheels, provided on a trailer that is pulled by a tractor provided with front and rear wheels. A trailer axle lifting device that drives the lifting and lowering traveling axle to a grounding position where the traveling wheel contacts the road surface and a retracted position where the traveling wheel moves away from the road surface,
An actuator that moves forward and backward by fluid pressure to drive the elevating traveling axle to the grounding position and the retracted position;
A first control valve provided in a fluid pressure circuit connecting the actuator and a fluid pressure source, wherein the first control valve is switched between a position for supplying fluid to the actuator and a position for discharging fluid in the actuator;
An operation switch for operating switching of the first control valve;
Vehicle stop detection means for detecting whether the trailer is in a vehicle stop state;
When it is not detected by the vehicle stop detection means that the trailer is in a vehicle stop state, the drive of the liftable travel axle to the retracted position is interrupted, and the liftable travel axle is placed in the grounding position. And control means
When the tractor and the trailer are placed on a measurement table and the total vehicle weight is measured, the distance from the front wheel of the tractor is longer than the length of the measurement table and the liftable traveling axle that protrudes from the measurement table is A trailer axle lifting device capable of measuring the total vehicle weight by driving to the retracted position. 2. The trailer axle lifting apparatus according to claim 1, wherein the trailer axle lifting apparatus is provided in a fluid pressure circuit that connects a suspension mounted on the lifting traveling axle and a fluid pressure source, and the lifting traveling axle is the grounding position. Thus, when the operation switch is operated, the fluid in the suspension when the operation switch is operated so that the fluid is supplied to the suspension when the operation switch is operated and the liftable traveling axle is in the retracted position. A second control valve that is switched to a discharge position for discharging
Under the state where it is not detected that the trailer is in a vehicle stop state by the vehicle detection means, the switching of the second control valve to the discharge position is interrupted, and the liftable traveling axle is A trailer axle lifting apparatus comprising: the control means for setting a grounding position.   3. The trailer axle lifting device according to claim 1 or 2, wherein the vehicle stop detection means is a parking brake sensor that detects whether or not a parking brake that applies a braking force to the traveling wheels is operating. Trailer axle lifting device.   3. The trailer axle lifting device according to claim 1, wherein the vehicle stop detection means is a vehicle speed sensor that detects a vehicle speed of the trailer.   The trailer axle lifting device according to any one of claims 1 to 4, further comprising: the operation switch that opens and closes an electric circuit that connects the control valve including a solenoid valve and a power source. Axle lifting device.   6. The trailer axle lifting apparatus according to claim 5, further comprising a relay switch as the control means for opening and closing the electric circuit in response to a signal from the vehicle stop detection means.

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