Idler guide unit

An idler guide unit for crawler type traveling apparatuses which attains the facilitation of clearance regulating operations and the reduction, which is owing to the facilitation of the mentioned operations, of traveling noise. This idler guide unit is formed so that the clearance regulating operations are carried out by using tapering blocks 26, position regulators 41, 50 for the tapering blocks 26 being also provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an idler guide unit.

2. Description of the Related Art

As known well, in a crawler type traveling apparatus in a bulldozer, a power shovel and a crawler crane, an axis-to-axis distance of a sprocket and an idler is set so that a crawler normally has a desired degree of slack. This enables a slackened-side portion of the crawler to be rendered free from the reception of the application of a tensile force, though a driving-side portion (a side-portion that is pulled by the sprocket) of the crawler encounters the occurrence of a tensile force. Thus, the reduction of the internal friction of the crawler and the traveling resistance thereof due to the internal friction thereof is attained.

When earth and sand and rocks eat into, for example, meshed portions of the sprocket and crawler during a practical operation of the crawler, a tensile force (which will hereinafter be referred to as shoe tension) occurs over the whole circumference of the crawler. When the shoe tension in such a case is not higher than a predetermined level, the earth and sand and rocks eating into the meshed portions mentioned above are collapsed with the above-mentioned axis-to-axis distance kept unchanged. Thus, the slippage (which will hereinafter be referred to as a jump) of the meshed sprocket and crawler and the dislocation of the crawler are prevented. When the shoe tension becomes not lower than a predetermined level, the idler is reversed (which will hereinafter be referred to as recoiling), and the traveling apparatus is thereby protected. As a means for enabling such inconveniences to be eliminated, an idler guide apparatus supporting bearings for the idler so that the bearing can be slid in the longitudinal direction of the traveling apparatus.

However, in this structure, the idler guide unit is used as it is exposed to dust or the weather, so that the width of a clearance between the crawler and sprocket is liable to increase. In the clearance width-increased condition, the traveling noise increases due to the striking sounds occurring in the clearance during a movement of a crawler type traveling apparatus, and this would give rise to a serious trouble. In order to regulate the width of the clearance, it is necessary to remove the idler of large mass, and repair a worn part by welding or replace such a part. Therefore, the maintenance and repair work for the crawler costs a great deal.

The patent literature1[JP-A-5-40090 (pages 6 to 7,FIG. 1andFIG. 2)] discloses a structure as an example of a means for solving these problems which attains the restraining of an increase in width of a lateral clearance in an idler guide unit by increasing the width of a vertical clearance therein, and the disusing of a lateral-clearance regulating operation.

An example of a related art idler guide unit will be described with reference toFIGS. 5 to 6by taking this patent literature1as an example literature.

FIG. 5is a side view of a crawler type traveling apparatus to which a related art idler guide unit is applied, andFIG. 6a sectioned front view, a drawing illustrating the same idler guide unit, taken along the line L—L inFIG. 5.

First, referring toFIG. 5, a traveling apparatus is formed by providing a sprocket at a rear end portion of a track frame61, an idler65at a front end portion thereof, lower rolling wheels15at a lower portion thereof, and upper rolling wheels16at an upper portion thereof respectively, and by winding a crawler17around the sprocket, idler65, lower rolling wheels15and upper rolling wheels16.

The track frame61is provided on an upper portion thereof with a spring box68, and the idler65is rendered able to be recoiled by a spring (not shown) in the spring box68, the idler65being formed so that the idler65can be recoiled as the idler is guided by an idler guide unit70provided on bearings.

Next, referring toFIG. 6, the idler guide unit70has bearings72fastened by bolts76to left and right end portions of an idler shaft71which supports the idler65thereon. The bearings72are provided with upper guides73, to which guide plates75are fixed, and lower guides74, and the upper and lower guides are engaged with guide plates82on an upper surface of the track frame and guide brackets84on inner surfaces of the track frame respectively. A vertical movement of the idler65is restricted by this arrangement.

Guide brackets90,90are fastened by bolts93to outer end surfaces of the left and right bearings72,72respectively via shims92,92. Guide surfaces91,91of the guide brackets90,90are engaged with guide plates83,83on left and right outer side surfaces81,81of the track frames80via clearances S1. A lateral movement of the idler65is restricted by this arrangement.

The left and right outer side surfaces81,81of the track frame80and outer side surfaces of the guide plates83,83are formed into downwardly divergent surfaces, i.e. left and right tapering surfaces.

When the upper guides73of the bearings72and the guide plates82on the upper surfaces of the track frames in the above-described structure shown inFIGS. 5 to 6are worn, the bearings72are moved down. This causes the clearances S1between the inclined guide plates83,83on the left and right outer side surfaces81,81of the track frames80and the guide surfaces91,91of the guide brackets90,90to decrease. As a result, even when the guide plates83,83and guide surfaces91,91are worn, the width of the clearances S1does not increase, so that operations for regulating the lateral width of the clearances are said to become unnecessary.

However, the construction of the related art idler guide unit70shown inFIGS. 5 to 6has the following problems.

(1) The idler65does not always receive a downwardly directed force. For example, when a working vehicle runs on a wasteland, the idler65is thrust up due to projecting parts of the ground surface. When the traveling apparatus is moved rearward, shoe tension is applied to an upper portion of the crawler of the apparatus, and the idler65is lifted. Consequently, when the width of a vertical clearance of the idler guide unit increases, vertical movements of the idler65become large during the running of the working vehicle, and traveling noise increases due to the striking sounds of the clearance-forming parts occurring during such large vertical movements of the idler65.

(2) In the condition described in (1) above, the lateral clearance reducing effect of the inclined surfaces of the guide plates83,83is not displayed but the lateral vibration of the idler65occurs. The striking sounds of the clearance-forming parts also occur during such time.

(3) When a load is imparted to a working machine in a working vehicle, a crawler type traveling apparatus retains the stability of front and rear portions of the vehicle by using the idler and sprocket as front and rear fulcrums. Therefore, in general, the progress of the wear on the vertical guide portions75,74,82,84of an idler guide unit is speedier than that of the wear on the lateral guide portions83,83,91,91thereof. On the other hand, the above-mentioned structure of the related art idler guide unit does not have clearance regulating means for the vertical guide portions75,74,82,84, so that the clearances are left in an increased state unless the guide plates75,82are replaced. As a result, the crawler type traveling apparatus is a crawler type traveling apparatus generating a large traveling noise.

(4) As a clearance regulating method, repairing the guide plates75,82by welding, or replacing the same is needed. In order to carry out the repairing or replacing of the guide plates, the idler of large mass has to be removed. Therefore, the crawler type traveling apparatus necessarily becomes a crawler type traveling apparatus of a high maintenance and repair cost.

SUMMARY OF THE INVENTION

The present invention has been made with the inventor's attention paid to these problems, and one of the objects of the present invention is to provide an idler guide unit for crawler type traveling apparatuses which attains the facilitation of clearance regulating operations and the reduction of traveling noise which is ascribed to the facilitation of clearance regulating operations.

To achieve this object, a first invention provides an idler guide unit for crawler type traveling apparatuses which is formed so that clearance regulating operations are carried out by using tapering blocks.

According to the first invention, the tapering blocks are provided, for example, between bearings, which support left and right end portions of an idler shaft, and upper surfaces of track frames, and guide plates contacting each other are fixed to lower surfaces of the tapering blocks and upper surfaces of the track frames. Therefore, even when the guide plates are worn to cause the idler shaft to move down, the position of the idler shaft can be corrected in the upward direction by moving the tapering blocks. This enables increased portions of the clearances, which occur due to the wear on the guide plates, in the idler guide apparatus to be corrected.

In a second invention, which is in accordance with the idler guide unit of the first invention, position regulators for the tapering blocks are provided.

According to the second invention , the effect of easily correcting the position of the idler of large mass in the upward direction can be obtained in addition to the operation and effect of the first invention by shifting the positions of the tapering blocks by using the tapering block position regulators. This enables the elimination of increased portions of the widths of the clearances, which occur due to the wear on the guide plates, in the idler guide unit to be attained easily.

As a result, an idler guide unit for crawler type traveling apparatuses, attaining the facilitation of the regulation of widths of the clearances and the reduction of the level of traveling noise can be provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first and second modes of embodiment of the idler guide unit according to the present invention will now be described in detail with reference toFIGS. 1 to 5with a bulldozer taken as an example to which the invention is applied.

First, the first mode of embodiment will be described with reference toFIGS. 1 to 3.

FIG. 1is a side view of a bulldozer having a crawler type traveling apparatus to which the idler guide unit according to the present invention is applied,FIG. 2a detail drawing in side elevation of a portion P ofFIG. 1of the first mode of embodiment of the idler guide unit according to the present invention, andFIG. 3a sectioned rear view taken along the line M—M inFIG. 2. The constituent elements of this embodiment identical with those of the idler guide unit ofFIGS. 5 and 6will be represented by the same reference numerals, and the description of such elements will be omitted.

First, referring toFIG. 1, a bulldozer1has a longitudinally elongated frame2in a central portion thereof, and crawler type traveling apparatuses10fixed to left and right side portions of the frame2. An idler is provided longitudinally movably at a front end portion of a track frame11of each crawler type traveling apparatus10via an idler guide unit20A or20B. The idler can be recoiled when a recoil spring14in the track frame11is bent.

Referring toFIGS. 2 to 3, the idler guide unit20A is formed by fixedly mounting by bolts25,25bearings21on left and right end portions of an idler shaft18on which an idler13is supported, fastening rails23,24by bolts25,25to lower surfaces of flange portions21a,21bprojecting in the outward direction of the bearings21and having longitudinally extending inclined surfaces, fixedly fitting upper portions of tapering blocks26, the tapering surfaces of which are formed by inclined surfaces26aand bottom surfaces26b, in grooves23a,24aof the rails23,24so that the upper portions of the tapering blocks26can be slid in the longitudinal direction, bringing slide plates fixed to lower surfaces of the tapering blocks26into contact with slide plates fixed to upper surfaces of the track frames11, supporting the bearings21on the tapering blocks26, and enabling vertical positions of the bearings21to be regulated by longitudinally moving the tapering blocks26.

Hook portions21care formed at lower portions of the bearings21, and guide plates31fixed to upper surfaces of the hook portions21care opposed via clearances (or clear spaces) S2of a predetermined width to guide plates33fixed to lower surfaces of brackets32provided on inner side surfaces of the track frames. The width of the clearances S2can be selected arbitrarily by regulating the vertical position of the bearings21on the basis of longitudinal movements of the tapering blocks26.

As a position regulator for each tapering block26, a regulating bolt41, on which a lock nut42is mounted, is screwed in a threaded hole23cmade in a projection23b, which is formed on a rear portion of the tapering block26, of the rail23. The regulating bolt41is adapted to regulate the longitudinal position of the tapering block26, and the resultant position is fixed by the lock nut42. A spring43is adapted to restrain an unnecessary forward movement, i.e. play of the tapering block26.

Guide brackets36are fastened to outer end surfaces of the left and right bearings21,21via shims37by a required number of bolts38, and guide surfaces36aof the guide brackets36are opposed via clearances (or clear spaces) S3to guide plates39fixed to outer side surfaces of the track frames11, the width of each clearance S3being able to be regulated by increasing or decreasing the thickness of the relative shim37.

When the width of the clearance S2in the above-described structure of the first mode of embodiment shown inFIGS. 1 to 3increases due to the wear on the guide plates27,28,31,33which restrict the vertical movements of the idler, the clearance S2can be regulated easily by pushing out the tapering block26forward by the regulating bolt41. When the width of each clearance S3increases due to the wear on the guide plates39,39, which are adapted to restrict the lateral movements of the idler, and the guide surfaces36a,36a, the width of the clearance S3can be regulated easily by increasing or decreasing the thickness of the relative shim37.

Next, the second mode of embodiment will be described with reference toFIG. 4.

FIG. 4is a detail drawing in side elevation showing a portion, which corresponds to the part P ofFIG. 1, of the second mode of embodiment of the idler guide unit according to the present invention. The constituent elements shown inFIGS. 1 to 3andFIGS. 5 to 6and identical with each other will be represented by the same reference numerals, and a description thereof will be omitted.

Referring toFIG. 4, an idler guide unit20B is provided with a grease cylinder50in a recess21dof a bearing21which is at the rear side of a tapering block26, the grease cylinder being fixed to a bracket55by bolts56to constitute a position regulator for a tapering block26. When grease is injected into a grease nipple52with a valve screw53of the grease cylinder50loosened, a piston51can be pushed out. This enables the position of the tapering block26to be regulated by the piston51.

In the structure of the second mode of embodiment shown inFIG. 4, the regulation of the width of a clearance S2becomes able to be made easier.

In the above-described structure, an example using a grease cylinder50is described as the position regulator for the tapering block26. The position regulator is not limited to a regulator using the grease cylinder50. The position regulator for the tapering block26may be formed by providing, for example, a hydraulic cylinder (not shown), and connecting this hydraulic cylinder to a hydraulic pressure source (not shown) in a vehicle body (not shown) via a pipe (not shown).

As a result, an idler guide unit for crawler type traveling apparatuses which attains the facilitation of the clearance regulating operations and the reduction, which is owing to the facilitation of the clearance regulating operations, of traveling noise can be provided.

The above is a description of modes of embodiment of the idler guide unit for a crawler type traveling apparatus of, for example, a bulldozer. The crawler type traveling apparatus to which the idler guide unit is applied is not limited to the crawler type traveling apparatus of a bulldozer. This idler guide unit can be applied universally to other kind of crawler type traveling apparatus, and used practically in the same manner as in the above-mentioned embodiments. Moreover, the same operation and effect as mentioned above can be obtained.