US3522897A

US3522897A - Kickout control for bucket loaders

Info

Publication number: US3522897A
Application number: US732662A
Authority: US
Inventors: Allan L Freedy
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1968-05-28
Filing date: 1968-05-28
Publication date: 1970-08-04
Anticipated expiration: 1987-08-04
Also published as: GB1240952A; ES367609A1

Description

Aug. 4, 1970 A. L. FREEDY KICKOUT CONTROL FOR BUCKET LOADERS 2 Sheets-Sheet 1 Filed May 28, 1968 INVENTOR ALLAN L. FREEDY 15v} VW hi-r ATTORNEYS B Y 9- a I l Aug. 4, 1970 A. L. FREEDY 3,522,897

KICKOUT CONTROL FOR BUCKET LOADERS Filed May 28, 1968 2 Sheets-Sheet 3 RESERVOlR INVENTOR ALLAN L. FREEDY ATTORNEYS US. Cl. 214-764 Claims ABSTRACT OF THE DISCLOSURE A bucket loader of the type having a bucket pivotally supported on a pair of lift arms, a tilt motor connected to the bucket by means of tilt linkage and tilt controls operable into a detent position for causing the tilt motors to pivot the bucket forwardly on its lift arms as for dumping. The tilt control is released from its detent position to terminate forward tilting of the bucket at an appropriate position relative to the lift arms in response to a kickout valve mounted on the lift arm and actuated by contact with a portion of the tilt linkage.

Numerous controls are available on bucket loaders for automatically positioning the bucket in order to decrease the manipulative duties of the operator and to improve operating efiiciency of the machines. The present invention is particularly concerned with a control for terminating forward tilting motion of the bucket in a position suitable for dumping during its loading cycle. In the prior art, this function is commonly performed by mechanical stops located on the lift arms and contacted by the tilt linkage as the bucket approaches its dump position. The operator can also perform this function by manually shifting the tilt control lever to the hold position. Hydraulic tilt controls are indirectly responsive to the engagement of the tilt linkage with the mechanical stops, by means of a resulting pressure rise in the fluid system, to terminate forward tilting of the bucket. However, as the size of the bucket loaders in increased, this manner of stopping the bucket causes severe jarring of the loader and the operator and creates undesirable stresses in the tilt and lift linkages for the loader. Repetition of the jarring contact with the stops tends to reduce operator efficiency as well as being a source of failure for various components of the loader. Thus, one object of the present invention is to normally terminate forward tilting of the bucket by other than the mechanical stops employed in the prior art.

It is another object to provide kickout means to which the tilt controls are directly responsive to terminate forward tilting of the bucket in a selected position relative to its lift arm means.

It is another object of the invention to normally terminate forward tilting motion of the bucket just prior to engagement with the mechanical stops regardless of the elevation of the bucket on its lift arms.

It is another object to provide means for selectively overriding the kickout control so that the operator can employ the mechanical stops when necessary to loosen material from the bucket for example.

The present invention overcomes the problems and fulfills the objects discussed above by providing a kickout which is actuated when the bucket is tilted forwardly to a selected position relative to the lift arms. Forward tilting of the bucket is preferably terminated just prior to contact of the bucket or its tilt linkage with suitable mechanical stops. Additional means permits selective overriding of the kickouts so that the mechanical stops may be employed to loosen material tending to stick to the bucket.

Other objects and advantages of the invention are made United States Patent 0 ice apparent in the following description having reference to the drawings wherein:

FIG. 1 is a side view in elevation of the forward end of a bucket loader including a solid line representation of its bucket in a normal loading position and a broken line representation of the bucket in its dump position at a selected elevation; and

FIG. 2 is a generally schematic representation, with parts in section, of a hydraulic tilt control system for the loader of FIG. 1.

A bucket loader of the type illustrated in FIG. 1 has a bucket 11 pivotally supported upon a pair of lift arms, one of which is indicated at 12, with hydraulic lift motors, as indicated at 13, for varying the elevation of the bucket by means of the lift arms. A hydraulic tilt motor 14 is mounted on each lift arm and is interconnected with the loader 10 and bucket 11 by means of tilt linkage 16. The tilt linkage includes a lever 17 pivotally secured to each lift arm as at 18. Each of the levers 17 is pivotally connected at 19 to a rod 21 of one of the tilt motors 14 and at 22 to a link 23 which is also pivotally connected to the bucket at 24. The bucket is also shown at 11 in a dump position at a selected elevation with its tilt and lift components also shown by similar primed numerals. A mechanical stop 26 is suitably mounted on each lift arm 12 for engagement by a surface 27 on one of the levers 17 with the bucket generally in its dump position indicated at 11'.

The present invention provides a kickout valve, indicated at 28, to terminate forward tilting of the bucket in its dump position and just prior to engagement of the lever 17 with the mechanical stop 26 regardless of the elevation of the bucket on its lift arms. The kickout valve 28 is suitably positioned upon one of the lift arms 12 for actuating engagement with a cam surface 29 on tilt linkage lever 17 as the bucket approaches its dump position 11' and just prior to engagement of the lever surface 27 with the mechanical stops 26 (see the broken line representation of the bucket linkage in FIG. 1). With the kickout valve 28 positioned for actuation in this manner, forward tilting of the bucket is always terminated with the bucket in a selected position relative to the lift arms so that contact with the mechanical stops 2-6 is normally avoided. Provision is made for overriding of the kickout valve 28 to permit loosening of material from the bucket by means of contact with the mechanical stops as is discussed below with reference to FIG. 2. It is readily apparent that the same function could be achieved with the kickout valve positioned forwardly on the lift arms for actuating engagement with the bucket. However, the present positioning of the kickout valve tends to reduce the possibility of its being damaged by contact with the ground or debris from the bucket.

The hydraulic control circuit for the tilt motors 14 includes a fluid reservoir 31, a pump 32 and a control valve 33 for selectively regulating fluid flow from the pump 32 to one end of the tilt motor 14 and communicating the other end of the tilt motor to drain. The control valve 33 defines a bore 34 for reciprocably receiving a spool 36. The control spool 36 is normally urged into a Hold position, indicated at H, by a centering spring 37. The control spool 36 is linked to a pivotal level 38 which is positioned by a control element 39. Counterclockwise rotation of the lever 38 urges the spool into a Rackback position, indicated at R, so that the control valve 33 communicates pump fluid to the rod end of the motor 14 while communicating the head end of the motor to drain for causing retraction of the motor. Forward tilting of the bucket for dumping results from extension of the tilt motors 14 when the lever 38 is rotated clockwise to move the spool to a Dump position, indicated at D. A roller 41 is mounted on a pivotal member 42 which is urged in clockwise rotation by a spring 43 so that the roller 41 comes into engagement with a cam surface 44 on the lever 38 when the control valve spool 36 is moved into its position D. Detenting of the lever 38 by means of the roller 41 maintains the control spool 36 in its rightward position for continued forward tilting of the bucket without the operator being required to maintain the position of the lever 38.

To release the roller 41 from its detent engagement with the lever 38 as the bucket approaches its dump position (see FIG. 1), a hydraulic slave cylinder 46 has a reciprocable spool 47 coupled to the pivotal member 42 and is associated for hydraulic response to the kickout valve 28. The hydraulic kickout valve 28 has a reciprocable spring loaded spool 48 normally extending toward the tilt linkage lever 17. In FIG. 2, the tilt linkage lever 17 is shown in a position just prior to engagement of its cam surface 29 with a roller 49 mounted on the extended end of the spool 48. A conduit 51 communicates the kickout valve 28 with the rod end of the tilt motor 14 while another conduit 52 communicates the hydraulic kickout valve 28 with the slave cylinder 46. The spool 48 is normally urged by its spring into a position preventing fluid communication between the

conduits

51 and 52. Referring momentarily to FIG. 1, as the bucket is being tilted forwardly and approaches its dump position indicated at 11', gravity acts upon the bucket tending to cause extension of the hydraulic motors 14. Hydraulic pressure is created in the rod end of the motors and is communicated to the kickout valve 28 through the conduit 51. Engagement of the tilt lever cam surface 29 with the kickout spool 48 shifts the spool leftwardly and communicates fluid pressure from the conduit 51 to the slave cylinder 46 through the conduit 52. With the lever 38 rotated clockwise for detent engagement with the roller 41, the pivotal member 42 and the slave spool 47 are shifted leftwardly so that the conduit 52 is in communication with an intemal passage 53 formed in the slave spool 47. A restricted drain passage 54 in the slave cylinder 46 causes fluid pressure from the conduit 52 to enter the left end of the slave cylinder 46 through the passage 53 and shift the slave spool 47 rightwardly. This motion of the slave slave spool causes counterclockwise rotation of the pivotal member 42 against its spring 43 so that the roller 41 is released from detent engagement with the lever 38. The control valve spool 36 is then returned to its Hold position H by the centering spring 37 to terminate forward tilting of the bucket in the dump position shown in phantom lines in FIG. 1. Forward tilting of the bucket is preferably terminated just prior to engagement of the tilt lever surface 27 with the mechanical stop 26 as is also indicated in the broken line representation of FIG. 1. In this manner, the hydraulic tilt controls for the bucket .are directly responsive to the kickout valve 28 to normally prevent jarring contact with the mechanical stops 26. However, if it is necessary to jar the bucket in order to loosen material sticking to the bucket surfaces, the operator may cause the tilt linkage levers to come into contact with the stop 26 by manually maintaining the lever 38 in its Dump position D to override the hydraulic kickout valve 28.

What is claimed is:

1. A bucket loader of the type having a bucket pivotally supported on at least one lift arm for raising and lowering the bucket, comprising tilt linkage associated with the bucket,

motor means for pivoting the bucket in relation to the lift arm by means of the tilt linkage,

kickout means associated with the bucket and actuatable when the bucket reaches a predetermined dump position relative to the lift arm, the motor means being directly responsive to actuation of the kickout means to terminate forward tilting of the bucket, and

a mechanical stop for resisting forward tilting of the bucket just subsequent to operation of the kickout means, the motor means being capable of selective operation to override the kickout means and tilt the bucket forwardly for effective engagement with the stop.

2. The invention of claim 1 wherein the motor means has detent means for maintaining it in a condition to tlit the bucket forwardly and slave means operable to release the motor means from the detent in response to actuation of the kickout means.

3. The invention of claim 2 wherein the kickout means are mounted on the lift arm for actuatable engagement by forward tilting of the bucket.

4. The invention of claim 3 wherein a tilt linkage lever is mechanically connected to the bucket and pivotally supported on the lift arm to enter into actuating engagement with the kickout means as the bucket approaches its dump position and prior to engagement of the lever with the mechanical stop.

5. The invention of claim 2 wherein the kickout means and slave means are hydraulic cylinders.

References Cited UNITED STATES PATENTS 3,211,310 10/1965 McIndoo 214-764 3,402,846 9/1968 Goth 214764 3,429,471 2/1969 Austin et a1. 214764 X HUGO O. SCHULZ, Primary Examiner