Overspeed protection control for an engine

An overspeed protection control for an engine having a fixed displacement pump driven thereby by increasing loading on the engine when the engine speed is excessive comprising, a hydraulic circuit connected to the pump outlet for utilization of pumped fluid, means selectively operable to restrict flow in said circuit and increase back pressure on said pump, and means responsive to engine speed exceeding a predetermined value to render said flow restricting means operable.

An overspeed protection control for an engine which drives a fixed displacement pump for an implement circuit and a hydrostatic transmission including a pump and a motor comprising, a hydraulic implement circuit connected to the outlet of said fixed displacment pump, valve means selectively operable to increase pressure in said implement circuit and impose a load torque on said engine, and means responsive to the speed of the engine exceeding a predetermined value to render said valve means operable.

An overspeed protection control for an engine which drives a fixed displacement pump comprising, a hydraulic circuit supplied by the pump, an orifice in said circuit, a relief valve connected to sump, a pilot operated valve having a pair of ports for connection into said circuit and a third port for connection to said relief valve, and means for applying the differential pressure across said orifice to said pilot operated valve whereby a predetermined pressure differential caused by a predetermined fluid flow proportional to engine speed moves said pilot operated valve to direct excess fluid flow to the relief valve and cause a pressure rise in the hydraulic circuit to a valve determined by the setting of the relief valve and impose a load torque on the engine to reduce engine speed.

An overspeed protection control for an engine which drives a fixed displacement pump comprising, a hydraulic circuit supplied by the pump, valve means in said circuit including a valve member movable to a closed position against a valve seat to block flow through said circuit, a chamber housing said valve member, spring means in said chamber urging said valve member toward the valve seat, and means operable when the engine speed exceeds a predetermined value to cause fluid pressure build-up in said chamber and urge the valve member toward the valve seat to increase the load torque on the engine.

An overspeed protection control for a prime mover which drives at least one pump which can increase torque loading of the prime mover in response to a pressure rise comprising, a hydraulic circuit connected to the outlet of said pump, means ineffective on pressure in said circuit when the speed of the prime mover is below a predetermined value and selectively operable to cause an increase in pressure in said circuit and a resulting increase in load torque on the prime mover, and means responsive to the speed of the prime mover exceeding a predetermined value to render said first-mentioned means operable.