Deere + Company

Yifei Raymond Hou

Sanjay Ishvarlal Mistry

Mark Allen Bergene

Scott Allen Toppin

Derek Malcolm Eagles

A system for monitoring the charge flow in a hydrostatic system. The system provides a sharp edge orifice restriction in the drain from the hydrostatic pump, creating a back pressure in the drain that is proportional to the fluid flow through the drain. A pressure switch mounted in the pump case, or in the drain, detects the back pressure in the drain. The pressure switch is designed to be activated at a back pressure that corresponds to the intended charge flow at a specific engine speed. During operation, if the back pressure is not sufficient to cause the pressure switch to be activated at the predetermined engine speed or at a faster engine speed, the charge flow is not sufficient and a warning signal is generated.

Hydrostatic system with charge flow monitoring

A hydraulic system having a standpipe in a sump with ports on the side of the standpipe and one smaller port on the top of the standpipe. The majority of the oil flows into the standpipe through the side ports thereby reducing the downward suction and flow at the top of the standpipe to eliminate the formation of a vortex at the top of the standpipe. As a result, less air is drawn into the oil producing a more consistent oil/air mixture and more consistent sump oil level.

Hydraulic system sump standpipe

A control system is provided for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump is responsive to steering control signals representing a status of an operator manipulated steering wheel. The steering motor provides an input to a differential track drive mechanism which responds to manipulation of the steering wheel and drives left and right tracks to turn the vehicle. The control system includes a control unit which receives signals from an engine speed sensor, a steering motor rotation speed and direction sensor, and the steering control signals. The control unit, when the steering control signals indicate that the steering wheel is turned in a direction opposite to a direction of rotation of the steering motor, generating and saving a first ratio value representing a ratio of the motor speed to the pump speed. Then, if the steering control signal is unchanged after a certain time duration, the control unit generates and saves a second ratio value representing a later ratio of the motor speed to the pump speed. The control unit then calculates a difference value representing a difference between the first and second ratio values, and generates a fault signal if the difference value has a magnitude which is less than a predetermined magnitude. Thus, the control system generates a fault signal when the sensed signals indicate that the steering pump swashplate position is not changing as it should in response to changes in steering wheel position.

Tracked vehicle steering system with failure detection

A supplemental charge for a hydrostatic steering system is provide by coupling the output of the transmission oil pump to the outlet of the steering charge pump and providing a check valve to prevent oil flow from the transmission oil pump to the steering charge pump unless the charge pump outlet pressure drops below the operating pressure of the transmission pump. When the steering charge pressure does drop below the transmission oil pressure, the check valve opens and oil is provided to the main steering pump by the transmission oil pump. A pressure transducer in the oil line activates a warning signal in the event the check valve is open more than a few minutes to alert the vehicle operator to a system failure.

Supplemental charge for hydrostatic steering system

A control system is provided for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump is responsive to steering control signals representing a status of an operator manipulated steering wheel. The steering motor provides an input to a differential track drive mechanism which responds to manipulation of the steering wheel and drives left and right tracks to turn the vehicle. The control system includes a control unit which receives signals from an engine speed sensor, a steering motor rotation speed and direction sensor, and the steering control signals. The control unit calculates a motor speed threshold value as a function of sensed engine speed and steering control signals, and generates a fault signal as a function of a relationship between the steering motor speed signal and a motor speed threshold value. The control unit generates an overspeed fault signal when the steering motor speed signal is greater than the motor speed threshold value or less than a negative motor speed threshold value, and generates a data conflict fault signal when the steering motor speed signal is less than a negative minimum motor speed threshold value or greater than a minimum motor speed threshold value. The control unit, when the vehicle is not being commanded to turn by the steering control signals, generates a minimum threshold value, and generates an overspeed fault signal when the motor speed signal is greater than the minimum threshold value or is less than a negative minimum threshold value.

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Waterloo, IA, United States of America

Yifei Raymond Hou