Working machine
A working machine having a body supported on a ground engaging structure and a working arm mounted to the body so as capable of performing working operations. The working machine having a drive arrangement to propel the working machine including a prime mover and a hydrostatic transmission including at least one hydraulic pump driven by the prime mover, and at least one motor driven by hydraulic fluid. The working machine also having a hand throttle for selectively setting the power output of the prime mover, a foot throttle for dynamically adjusting the power output of the prime mover in a first mode of operation, wherein the transmission is configured to operate in a second mode of operation when a predetermined criterion is met, and in the second mode the foot throttle directly controls the speed of movement of the ground engaging structure.
1. A working machine comprising:
a ground engaging structure;
a body supported on the ground engaging structure
a working arm mounted to the body so as capable of performing working operations; and
a drive arrangement for moving the ground engaging structure to propel the working machine, the drive arrangement including a prime mover and a hydrostatic transmission comprising at least one hydraulic pump driven by the prime mover, and at least one motor driven by hydraulic fluid supplied by the at least one hydraulic pump;
a hand throttle for selectively setting the power output of the prime mover,
a foot throttle for dynamically adjusting the power output of the prime mover in a first mode of operation;
wherein the transmission is configured to operate in a second mode of operation when a predetermined criterion is met, and in the second mode the foot throttle directly controls a speed of movement of the ground engaging structure; and
wherein the hand throttle is configured to set a maximum speed of movement of the ground engaging structure in the second mode.
2. The working machine according to claim 1 , wherein the predetermined criterion is a non-zero input from the hand throttle, and wherein the non-zero input from is above a predetermined level.
3. The working machine according to claim 1 , wherein the predetermined criterion is an input from a site/highway selector.
4. The working machine according to claim 1 , configured to control speed of movement by varying hydraulic fluid flow between a directional control valve and a hydraulic motor connected to the ground engaging structure separately from prime mover speed.
5. The working machine according to claim 4 , configured to vary hydraulic flow in response to load imposed on the drive arrangement, so as to maintain a substantially fixed predetermined relationship between foot throttle demand and the speed of the ground engaging structure.
6. The working machine according to claim 5 further comprising a wheel speed sensor and/or a ground speed sensor such that the substantially fixed predetermined relationship may be maintained.
7. The working machine according to claim 1 , comprising two hydraulic motors, a first motor driving a front axle and a second motor driving a rear axle.
8. The working machine according to claim 7 , wherein the first motor is a low speed motor and the second motor is a relatively high speed motor.
9. The working machine according to claim 7 , wherein at least one of the first and second hydraulic motors is located proximate its respective axle.
10. The working machine according to claim 9 , wherein both motors are directly connected to their respective axles.
11. The working machine according to claim 8 , wherein the low speed motor comprises a reduction gear.
12. The working machine according to claim 1 , further comprising a second low pressure pump driven by the prime mover for providing hydraulic fluid for further working machine functions.
13. The working machine according to claim 12 , wherein the drive to the first and second pumps is in series.
14. The working machine according to claim 12 , wherein the drive to the first and second pumps is in parallel.
15. The working machine according to claim 1 , wherein the body comprises an undercarriage and a superstructure rotatable thereon.
16. The working machine according to claim 15 , wherein the prime mover, first hydraulic pump and first and second hydraulic motors are mounted in the undercarriage.
17. The working machine according to claim 1 , wherein the prime mover is mounted in a transverse direction to a fore-aft direction of the working machine.
18. A method of operating a working machine according to claim 1 , comprising the steps of: causing the transmission to enter the second mode of operation and operating the foot throttle to reposition the machine.
19. The working machine according to claim 1 , wherein the predetermined criterion is an input from the hand throttle above a predetermined level.
20. The working machine according to claim 1 , wherein in the second mode only the hand throttle is able to adjust the engine speed.