Hydraulic system for broadcast spreader

Claim 2

A hydraulic drive system for a spreader vehicle having an engine, a dispensing mechanism and conveyor means for delivering material to be spread to the dispensing mechanism; said system comprising first hydraulic motor means connected with said dispensing mechanism for driving said dispensing mechanism; second hydraulic motor means connected with said conveyor means for driving said conveyor means; a variable displacement pressure compensated pump for delivering hydraulic fluid at a variable rate substantially in accordance with demand by said motor means; hydraulic circuit means connecting said pump and said motor means and including a first hydraulic power line connected to the pump outlet, a first control valve connected to said power line for controlling fluid flow to said first motor means, a second power line in parallel with said first control valve for supplying fluid to said second motor means, and means connected to said second power line and to said pump including control valve means for providing a fluid pressure signal to said pump responsive to fluid flow through said valves for adjusting the pump displacement.

Claim 3

A system, as defined in claim 1, wherein said means for providing a fluid pressure signal to the pump comprises a second control valve connected between said second power line and said second motor means and a fluid pressure bypass line connected between said second power line and said pump.

Claim 4

A system, defined in claim 2, wherein said first valve comprises a manually adjustable pressure compensated bypass type flow control valve for maintaining a predetermined generally constant fluid flow to said first motor means for driving said dispensing mechanism at a substantially constant predetermined rate, and said second valve means comprises a servo adjustable pressure compensated by-pass type flow control valve responsive to signal means operable in accordance with the speed of the vehicle for varying the fluid flow to said second motor means for adjusting the speed of the conveyor means.

Claim 5

A system, as defined in claim 1, wherein said means for providing a fluid pressure signal to the pump comprises a second control valve connected between said second power line and said pump, said second power line being connected directly to said second motor means.

Claim 6

A system, defined in claim 4, wherein said first valve comprises a manually adjustable pressure compensated bypass type flow control valve for maintaining a predetermined generally constant fluid flow to said first motor means for driving said dispensing mechanism at a substantially constant predetermined rate, and said second valve means comprises a servo adjustable pressure compensated restrictive type flow control valve responsive to signal means operable in accordance with the speed of the vehicle for varying the fluid flow to said pump crankcase inlet which in turn controls flow to said second motor means for adjusting the speed of the conveyor means.

Claim 7

A system, as defined in claim 1, wherein said hydraulic circuit includes a hydraulic fluid reservoir, conduit means connecting an outlet of said first motor means back to said pump for recirculating fluid from said first motor means and additional conduit means connecting an outlet of said second motor means with said reservoir.

Claim 8

A system, as defined in claim 1, wherein said dispensing mechanism includes at least one broadcast spinner, and said first motor means includes at least one hydraulic motor.

Claim 9

A spreader for dispensing granular material on highways, farms and the like comprising a vehicle having an engine; a box on said vehicle for containing a supply of material to be dispensed; a dispensing mechanism mounted on said vehicle; a conveyor mounted on said vehicle for delivering materials to be spread from said box to said dispensing mechanism; a first hydraulic motor connected with said dispensing mechanism for driving said dispensing mechanism; a second hydraulic motor connected with said conveyor for driving said conveyor; a variable displacement pressure compensated pump mounted on said vehicle and drivingly connected with said engine for being driven at variable speeds in accordance with engine speed and for delivering hydraulic fluid at variable rates in accordance with demands by said motors; said pump including a pressurized crankcase having a fluid pressure signal inlet for controlling pump displacement; hydraulic circuit means connecting said pump and said motors and including a first valve connected with an outlet of said pump for controlling fluid flow to said first motor; said circuit means also including conduit means extending from a connection by passing said first valve to an inlet of said second motor; said first valve and said conduit means being in parallel; and said circuit means including a second valve connected between said conduit means and said crankcase inlet of said pump for controlling fluid flow to said second motor and for providing a fluid pressure signal to said inlet responsive to fluid flow through said valves for adjusting the pump displacement.

Claim 10

A spreader for dispensing granular material on highways, farms and the like comprising a vehicle having an engine; a box on said vehicle for containing a supply of material to be dispensed; a dispensing mechanism mounted on said vehicle; a conveyor mounted on said vehicle for delivering materials to be spread from said box to said dispensing mechanism; a first hydraulic motor connected with said dispensing mechanism for driving said dispensing mechanism; a second hydraulic motor connected with said conveyor for driving said conveyor; a variable displacement pressure compensated pump mounted on said vehicle and drivingly connected with said engine for being driven at variable speeds in accordance with engine speed and for delivering hydraulic fluid at variable rates in accordance with demands by said motors; said pump including a pressurized crankcase having a fluid pressure signal inlet for controlling pump displacement; hydraulic circuit means connecting said pump and said motors and including a first valve connected with an outlet of said pump for controlling fluid flow to said first motor; said circuit means also including conduit means extending from a connection by passing said first valve to an inlet of said second motor; said first valve and said conduit means being in parallel; and said circuit means including a second valve connected between said conduit means and said crankcase inlet of said pump for controlling fluid flow to said second motor and for providing a fluid pressure signal to said inlet responsive to fluid flow through said valves for adjusting the pump displacement.

Claim 11

A spreader as defined in claim 8, wherein said first valve comprises a by-pass type pressure compensated valve having a bypass port connected with said conduit means, and said second valve comprises a restrictive type pressure compensated valve.