JP3404700B2 - Parking brake release device for hydraulic traveling motor for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic traveling motor for traveling and driving an industrial vehicle such as a vibrating roller or a construction vehicle such as a backhoe, and more particularly, to a negative traveling motor. The present invention relates to a release device for releasing the parking brake from outside when towing a vehicle of this type having a parking brake of the type. 2. Description of the Related Art In general, in a hydraulic traveling motor of an industrial vehicle or a construction vehicle, in order to prevent the parked vehicles from escaping and causing an unexpected accident, it is necessary to prevent such accidents. In many cases, a so-called negative parking brake (hereinafter, simply referred to as a brake device), in which a parking brake is naturally applied by a spring force when hydraulic pressure for running drive is lost, is often incorporated. [0003] For this reason, even if these vehicles have a failure, for example, and are to be carried by another vehicle for repair, the vehicle must be towed because the brake device is in operation, that is, the brake is applied. Can not be done. Therefore, conventionally, in a hydraulic traveling motor having a brake device of this type, a bolt is screwed into a tightening piston of the brake device from the outside through a base plate of a motor case, and the tightening piston is compressed while the spring is compressed by the bolt. It is common to provide a brake release device that can be pulled to mechanically release the brake device. [0005] However, since this type of hydraulic traveling motor is used not only as a closed circuit but also as an open circuit, the hydraulic traveling motor climbs when used in this open circuit. When a counter load is applied on a slope or the like, there is a possibility that the vehicle will go backward. In order to prevent this, it is necessary to incorporate a counterbalance valve into the base plate of the motor case. In addition, especially in the case of a two-speed variable hydraulic traveling motor, it is necessary to further incorporate a switching valve for switching the rotation speed between high and low speeds with respect to the base plate. In the above, the counterbalance valve is required only when using an open circuit and is not required when using a closed circuit. Bulk and costly. Therefore, in order to make the base plate common regardless of the necessity of the counterbalance valve, a valve bore for the counterbalance valve is formed in the base plate, and the original function of the counterbalance valve is provided in the valve bore. The spool provided is simply replaced with a fixed type spool for the dummy which forms the oil passage by partitioning the valve bore of the counterbalance valve. As described above, regardless of the use of the closed circuit and the use of the open circuit, the base plate of the motor case is provided with a counter balance valve, a spool for a dummy, and a switching valve for switching the rotation speed between high and low speeds. Valves and oil passages for guiding pressure oil to the drive unit of the hydraulic motor and the tightening piston of the brake device via these valves are provided in a complicated manner. [0011] For this reason, in the case of a large hydraulic traveling motor used for a certain large vehicle, the base plate of the motor case becomes relatively large. It is relatively easy in terms of space to open an insertion hole for passing a brake release bolt. However, in the case of a hydraulic traveling motor for a small vehicle, not only the base plate itself is reduced, but also the area of valves and oil passages is not reduced. It is difficult to pass a brake release bolt through the base plate in terms of space. For this reason, in the conventional small hydraulic traveling motor with a brake device, a special casting for the base plate is newly blown to secure a space for passing the brake release bolt. I was As a result, there is a problem that it takes a great deal of trouble to make a new dedicated mold, and the cost must be increased. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vehicle in which a brake device can be externally released using a standard base plate for a small hydraulic traveling motor using a closed circuit and having a brake device. To provide a parking brake release device for a hydraulic traveling motor for a vehicle. In the present invention, it is an object of the present invention to insert a dummy spool into a valve bore of a counterbalance valve provided on a base plate of a motor case, and use the spool to insert the dummy spool into the valve bore. In a vehicle hydraulic traveling motor formed by partitioning an oil passage leading to a main port, a positioning pin for a detent is inserted through the base plate from outside through the base plate, and in this state, the vehicle is parked through the base plate and spool from outside. This is achieved by providing an insertion hole for screwing a brake release bolt into the brake pressing piston. According to the above construction, even if the hydraulic traveling motor is a small-sized hydraulic traveling motor that uses a mainstream closed circuit and has a brake device, the purpose is to pass the brake release bolt through the base plate. Without securing a space, it is possible to provide an insertion hole for passing a brake releasing bolt by using a dummy spool portion originally provided for the oil passage configuration. As a result, the base plate of the motor case does not need to be redesigned to pass the brake release bolt, and the brake release bolt can be passed using the standard base plate. Therefore, it is possible to manufacture such a small hydraulic traveling motor with a brake device at low cost. Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view of a two-speed variable vehicle hydraulic traveling motor. The hydraulic traveling motor comprises a motor case 1, a base plate 3 fastened to the motor case 1 by bolts 2, And a rotating drum 6 rotatably disposed around the motor case 1 with a bearing 4 and a floating seal 5 interposed therebetween. A plunger-type hydraulic motor 8 having a swash plate 7 which swings in one direction about an axis portion is accommodated inside the motor case 1. A multi-plate type parking brake device 9 is arranged between them. The brake device 9 is normally tightened by the force of a spring 11 interposed between the brake device 9 and the base plate 2 through the tightening piston 10, whereby the brake is applied. The part on the back side of the tightening piston 10 is as follows:
A brake release port 13 communicates with the brake release port 13 through an oil hole 12 provided from the motor case 1 to the base plate 3, and the brake is released by introducing pressure oil from the port 13 to the back side of the tightening piston 10. It is configured as a negative brake. As is apparent from FIG. 2, the base plate 3 is provided with two oil passages 16 and 17 having one ends open to the outside as main ports 14 and 15, respectively.
These oil passages 16 and 17 extend through a valve bore 18 for a counterbalance valve to a switching valve 19 for high / low speed switching. Both ends of the valve bore 18 are provided with caps 20,
21 and a spool 2 for dummy
2 is stored with caps 20 and 21 suppressed in movement, and the spool 22 partitions the two oil passages 16 and 17 from each other. These oil passages 16 and 17 communicate with hydraulic motors 8 on the motor case 1 side by oil passages 36 and 37 (not shown) provided in the base plate 2. The switching valve 19 for switching between high and low speeds has a pilot oil passage 23 for switching the switching valve 19, and is provided from the motor case 1 to the base plate 3, as shown in FIG. The oil passage 24 communicates with a portion of a pressing piston 25 for tilting the swash plate 7 of the hydraulic motor 8. The rotary drum 6 is connected to the output shaft 8a of the hydraulic motor 8 through a speed reduction mechanism 26 disposed inside, and the rotation speed of the hydraulic motor 8 is reduced to a predetermined speed by the speed reduction mechanism 26 and output. I have to do it. The above-mentioned hydraulic traveling motor is mounted on a vehicle by a flange 27 of the motor case 1 and a wheel is directly attached to a flange 28 of the rotary drum 6, or a sprocket wheel (not shown) meshing with the crawler. ) Is used. Thus, if pressure oil is selectively supplied to the main ports 14 and 15, this pressure oil is simultaneously sent to the port 13 through, for example, a shuttle valve (not shown). The attached piston 10 is retracted to automatically release the brake device 9. At the same time, these main ports 14
The hydraulic motor 8 starts rotating and driving in a predetermined direction with the pressure oil sent to the (forward side) or 15 (reverse side), and this rotation is reduced by the reduction mechanism 26 and transmitted to the rotating drum 6, and accordingly, The vehicle moves forward or backward. When the pressure oil is sent from the outside to the pilot oil passage 23 to switch the switching valve 19 during the forward movement of the vehicle, the pressure oil sent to the main port 14 acts on the pressing piston 25 to obliquely move. The plate 7 operates in a direction to reduce the tilt angle, the rotational speed of the hydraulic motor 8 increases, and the vehicle speed increases. Next, when the supply of pressure oil is stopped to stop the running vehicle, the rotation of the hydraulic motor 8 stops and the vehicle stops. At the same time, the tightening piston 10 is pressed by the spring 11 to return, and the force of the spring 11 acts on the brake device 9 from the tightening piston 10 to automatically apply a brake. As described above, in the above-described hydraulic traveling motor, the brake device 9 automatically operates at the same time as the stop of the vehicle. If you try to carry it, you cannot carry it because the brakes are on. In order to avoid such a situation, in the present embodiment, as shown in FIG. 3, the central portion of the spool 22 housed in the valve bore 18 of the base plate 3 is externally connected to the base plate 3. Positioning pin 30 for preventing rotation of the spool 22
And the insertion opening is closed with a cap 31. In this state, the spool 2
The insertion holes 32 and 33 are drilled from the outside to the base plate 3 and the spool 22 by using the portions on both sides of 2, and the external opening of the insertion hole 32 on the base plate 3 side is usually closed with a cap 34. When the vehicle is towed, the cap 34 is removed, and a bolt 35 for releasing the brake is inserted from the outside through the insertion holes 32 and 33 as shown in FIG. The screw 9 is screwed into the tightening piston 10 and turned, and the brake is mechanically released by pulling the tightening piston 10 against the spring 11 (see FIG. 1). Thus, the brake release bolt 35
Even if a small hydraulic traveling motor is difficult to insert through the space, the brake can be easily released by inserting the bolt 35. As described above, according to the present invention,
Originally, the dummy spool provided on the base plate for the oil passage configuration was used to provide an insertion hole for passing the brake release bolt, so a special space for the base plate was secured. Without this, the insertion hole can be easily provided. As a result, even if the hydraulic traveling motor is a small-sized hydraulic traveling motor that uses a mainstream closed circuit and has a brake device, a standard base plate can be used without changing the base plate of the motor case exclusively. Through which the bolt for releasing the brake can be passed. Thus, when manufacturing this kind of small hydraulic traveling motor with a brake device, it is possible to use the casting material of the standard hydraulic traveling motor as it is at a low cost without newly producing a mold for the base plate. It becomes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional front view of a vehicle hydraulic traveling motor provided with a parking brake release device according to the present invention. FIG. 2 is a longitudinal sectional side view taken along line AA in FIG. FIG. 3 is a cross-sectional plan view of a main part taken along line BB in FIG. 2; FIG. 4 is a cross-sectional plan view of a main part showing a state in which a brake releasing bolt is screwed into a piston of the brake device. [Description of Signs] 1 Motor case 3 Base plate 9 Brake device 14, 15 Main port 16, 17 Oil passage 18 Valve bore 22 Dummy spool 25 Pressing piston 30 Positioning pins 32, 33 Insertion hole 35 Brake release bolt

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-57071 (JP, A) JP-A 64-49672 (JP, U) JP-A 58-157760 (JP, U) JP-A 58-157760 163729 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16D 55/40 F16H 61/40

Claims (1)

(57) [Claim 1] A dummy spool is inserted into a valve bore of a counterbalance valve provided on a base plate of a motor case, and the spool communicates oil into the valve bore with a main port. In a vehicle hydraulic traveling motor formed by partitioning a passage, a positioning pin for stopping rotation is inserted through the base plate from the outside through the base plate, and in this state, the brake is released from the outside through the base plate and the spool to the pressing piston of the parking brake. A parking brake release device for a hydraulic traveling motor for a vehicle, comprising an insertion hole into which a bolt for screwing is inserted.