Speed control system for vehicle mounting a work performing device

Claim 2

In a vehicle having ground engaging propulsion means and a variable speed hydraulic motor for driving the same, a hydraulic pump for providing hydraulic fluid under pressure to the vehicle motor, a work performing means adapted to perform work as the vehicle moves along the ground, the improvement comprising: means for sensing the amount of work to be performed by the work performing means and for establishing a hydraulic fluid bypass about said hydraulic motor when the amount of work to be performed by the work performing means increases to decrease the speed of the vehicle.

Claim 3

The invention of claim 1 wherein said sensing and establishing means comprises a hydraulic conduit in parallel with said vehicle motor and valve means in said conduit; said valve means being operable to open when a predetermined pressure differential exists across the same.

Claim 4

The invention of claim 2 further including a control valve in said conduit; and means for opening said control valve when said work performing means is operative.

Claim 5

The invention of claim 2 wherein said valve means is adjustable whereby the pressure differential necessary to cause the same to open may be selectively varied.

Claim 6

A vehicle comprising: a frame; propulsion means mounted on said frame; a hydraulic vehicle drive motor connected to said propulsion means and operable when energized to cause said vehicle to move; a source of hydraulic fluid under pressure; means connecting said source to said hydraulic motor; work performing means connected to said frame to be movable with said vehicle and to perform work while said vehicle is moving; drive means for said work performing means including a hydraulic work performing motor adapted to receive hydraulic fluid under pressure; and vehicle speed control means comprising a bypass line across said hydraulic vehicle drive motor including an overflow valve for controlling the flow rate of hydraulic fluid through said bypass line, a bypass control valve in series therewith, and means connected to the high pressure side of said hydraulic work performing motor for sensing the pressure thereat and for opening said bypass control valve to permit diversion of hydraulic fluid from said hydraulic vehicle drive motor to thereby control the speed of the same and the speed of the vehicle.

Claim 7

A vehicle comprising: a frame; propulsion means mounted on said frame; a hydraulic vehicle drive motor connected to said propulsion means and operable when energized to cause said vehicle to move; a source of hydraulic fluid under pressure; means connecting said source to said hydraulic motor; work performing means connected to said frame to be movable with said vehicle and to perform work while said vehicle is moving; drive means for said work performing means including a hydraulic work performing motor adapted to receive hydraulic fluid under pressure; and vehicle speed control means comprising a bypass line across said hydraulic vehicle drive motor including an overflow valve for controlling the flow rate of hydraulic fluid through said bypass line, a bypass control valve in series therewith, and means connected to the high pressure side of said hydraulic work performing motor for sensing the pressure thereat and for opening said bypass control valve to permit diversion of hydraulic fluid from said hydraulic vehicle drive motor to thereby control the speed of the same and the speed of the vehicle.