A drive, which permits a lowering in the feed pressure provided by the feed pump and, at the same time, effects a supply to the displacement unit of the drive which meets the demand with regard to pressure and delivery volume. This is achieved in that the displacement unit (5) is supplied with hydraulic energy by an electro-hydraulic supply unit (6) wherein the supply unit (6) comprises a hydraulic reservoir (9) and a non-return valve (18) and is connected to the feed pressure limiting valve (12), which is implemented as an electrically adjustable pressure limiting valve, wherein the hydraulic reservoir (9) is also connected to an electro-hydraulic pressure sensor (10), which outputs the electric signal thereof to an electric auxiliary controller (11), and wherein the electric auxiliary controller (11) drives the feed pressure limiting valve (12). These hydraulic drives are used for example, in self-propelled working machines.

A traveling hydraulic stepless transmission (HST), ensures stopping of a vehicle on a slope under high load conditions, maintains stopping the vehicle on flat ground under low load conditions, and enables smooth starting from a stop. The HST includes a neutral check valve (NCV) and an internal damping system (IDS). The NCV includes a first orifice that opens a first oil passage to a transaxle case when a pressure in the first oil passage is equal to or less than a predetermined pressure, and that connects the second oil passage to the transaxle case when a pressure in a second oil passage is equal to or less than the predetermined pressure. The IDS includes second orifices that connect a high pressure side of the oil passages to the transaxle case when a discharge rate of the hydraulic pump is equal to or less than a predetermined discharge rate.

A hydraulic system that has a hydraulic pump connected to and in communication with a hydraulic motor, at least one hydraulic cylinder, or both by a first conduit and a second conduit (i.e., a high side and a low side). The hydraulic system has a bypass valve connected to and in communication with the first conduit and the second conduit. The bypass valve has a preset pressure that is above a minimum low side pressure. When a shock load occurs in the hydraulic system and a related drop in pressure on the low side occurs, the bypass valve opens when the preset pressure is passed thereby preventing the pressure from dropping to the minimum low side pressure. The hydraulic system thereby avoids a low loop event that could cause damage to the hydraulic system without the presence of larger charge pumps or accumulators.

A hydraulic system that has a hydraulic pump connected to and in communication with a hydraulic motor, at least one hydraulic cylinder, or both by a first conduit and a second conduit (i.e., a high side and a low side). The hydraulic system has a bypass valve connected to and in communication with the first conduit and the second conduit. The bypass valve has a preset pressure that is above a minimum low side pressure. When a shock load occurs in the hydraulic system and a related drop in pressure on the low side occurs, the bypass valve opens when the preset pressure is passed thereby preventing the pressure from dropping to the minimum low side pressure. The hydraulic system thereby avoids a low loop event that could cause damage to the hydraulic system without the presence of larger charge pumps or accumulators.

A drive, which permits a lowering in the feed pressure provided by the feed pump and, at the same time, effects a supply to the displacement unit of the drive which meets the demand with regard to pressure and delivery volume. This is achieved in that the displacement unit (5) is supplied with hydraulic energy by an electro-hydraulic supply unit (6) wherein the supply unit (6) comprises a hydraulic reservoir (9) and a non-return valve (18) and is connected to the feed pressure limiting valve (12), which is implemented as an electrically adjustable pressure limiting valve, wherein the hydraulic reservoir (9) is also connected to an electro-hydraulic pressure sensor (10), which outputs the electric signal thereof to an electric auxiliary controller (11), and wherein the electric auxiliary controller (11) drives the feed pressure limiting valve (12). These hydraulic drives are used for example, in self-propelled working machines.

A drive, which permits a lowering in the feed pressure provided by the feed pump and, at the same time, effects a supply to the displacement unit of the drive which meets the demand with regard to pressure and delivery volume. This is achieved in that the displacement unit (5) is supplied with hydraulic energy by an electro-hydraulic supply unit (6) wherein the supply unit (6) comprises a hydraulic reservoir (9) and a non-return valve (18) and is connected to the feed pressure limiting valve (12), which is implemented as an electrically adjustable pressure limiting valve, wherein the hydraulic reservoir (9) is also connected to an electro-hydraulic pressure sensor (10), which outputs the electric signal thereof to an electric auxiliary controller (11), and wherein the electric auxiliary controller (11) drives the feed pressure limiting valve (12). These hydraulic drives are used for example, in self-propelled working machines.

A hydraulic motor circuit for driving an auger is disclosed. The circuit includes a hydraulic motor that receives oil from an oil supply via a supply line and returns oil to the oil supply via a return line. The circuit further includes a main stage pressure relief valve and a first pilot stage relief valve operable if pressure in the return line exceeds a predetermined value corresponding to an allowable inertia load acting on the motor, opening of the first pilot stage relief valve causing the main stage pressure relief valve to open, allowing flow to be diverted from the return line to the supply line and back to the motor. A control valve is configured to block flow to the first pilot stage relief valve when pressure, in the supply line is greater than pressure in the return line. If pressure in the return line exceeds pressure in the supply line, the control valve shifts open and exposes the first pilot stage relief valve to pressure in the return line.

A hydraulic motor circuit for driving an auger is disclosed. The circuit includes a hydraulic motor that receives oil from an oil supply via a supply line and returns oil to the oil supply via a return line. The circuit further includes a main stage pressure relief valve and a first pilot stage relief valve operable if pressure in the return line exceeds a predetermined value corresponding to an allowable inertia load acting on the motor, opening of the first pilot stage relief valve causing the main stage pressure relief valve to open, allowing flow to be diverted from the return line to the supply line and back to the motor. A control valve is configured to block flow to the first pilot stage relief valve when pressure, in the supply line is greater than pressure in the return line. If pressure in the return line exceeds pressure in the supply line, the control valve shifts open and exposes the first pilot stage relief valve to pressure in the return line.

A hydraulic system that has a hydraulic pump connected to and in communication with a hydraulic motor, at least one hydraulic cylinder, or both by a first conduit and a second conduit (i.e., a high side and a low side). The hydraulic system has a bypass valve connected to and in communication with the first conduit and the second conduit. The bypass valve has a preset pressure that is above a minimum low side pressure. When a shock load occurs in the hydraulic system and a related drop in pressure on the low side occurs, the bypass valve opens when the preset pressure is passed thereby preventing the pressure from dropping to the minimum low side pressure. The hydraulic system thereby avoids a low loop event that could cause damage to the hydraulic system without the presence of larger charge pumps or accumulators.

The invention relates to a hydrostatic drive as a whole system, comprising two fluidic displacement units (1, 3), which can be adjusted at least in respect of the volumetric flow and of which one is coupled to an input (9) and the other is coupled to an output (11) and which can be connected to each other in the manner of a closed fluidic circuit, to which a storage circuit (23) is connected, which has at least one storage device (33) and which is divided into a low-pressure side (27) and a high-pressure side (25), and comprising a valve control device (17) for controlling the whole system.