A hydraulic control assembly includes means for holding pressure in a cylinder to inhibit boom or arm drop of a machine in the event that a hose between the cylinder and a main control valve (MCV) ruptures. The pressure holding means of the hydraulic control assembly include a hydraulic valve and a parts-in-body check assembly both configured for insertion into a valve cavity defined by a valve body. The hydraulic valve comprises a proportional piloted valve that controls pressure.

In one or more embodiments, a system for predicting health of a hydraulic pump comprises a reservoir tank temperature sensor to measure a temperature of a reservoir tank. The system further comprises a hydraulic pump temperature sensor to measure a temperature of the hydraulic pump. Also, the system comprises a differential pressure sensor to measure a differential pressure across a filter associated with the hydraulic pump. Further, the system comprises a processor(s) to determine a differential temperature by subtracting the temperature of the reservoir tank from the temperature of the hydraulic pump, to compare the differential temperature to a differential temperature threshold, to compare the differential pressure to a differential pressure threshold, and to generate an alert signal indicating failure of the hydraulic pump, when the processor(s) determines that the differential temperature exceeds the differential temperature threshold and the differential pressure exceeds the differential pressure threshold.

A work vehicle includes: a hydraulic pump driven by an engine; a hydraulic actuator that is driven by hydraulic oil supplied from the hydraulic pump; a switching valve configured to switch from one to the other of a first state in which the hydraulic oil supplied from the hydraulic pump is supplied to a first channel and a second state in which the hydraulic oil supplied from the hydraulic pump is supplied to a second channel; a restriction operation device configured to generate an operation signal that restricts the drive of the hydraulic actuator; and a controller that controls the switching valve. The controller includes: an operation signal acquisition unit configured to acquire the operation signal; and an instruction output unit configured to output, to the switching valve, a control instruction that restricts the drive of the hydraulic actuator with the engine driving, in response to the operation signal.

The subject matter of this specification can be embodied in, among other things, an electrohydraulic positioning control system that includes a shuttle valve configured to direct fluid flow between a selectable one of a first fluid port and a second fluid port, and a fluid outlet configured to be fluidically connected to a fluid actuator, a first servo valve controllable to selectably permit and block flow between the first fluid port, a fluid source, and a fluid drain, a second servo valve controllable to selectably permit and block flow between the second fluid port, the fluid source, and the fluid drain, a first servo controller configured to provide a first health signal and control the first servo valve based on a second health signal, and a second servo controller configured to provide the second health signal and control the second servo valve based on the first health signal.

The subject matter of this specification can be embodied in, among other things, a method that includes actuating a closure member at a predetermined first velocity a predetermined first number of cycles between a first configuration and a second configuration, actuating the closure member at a predetermined second velocity a predetermined second number of cycles between the first and the second configuration, actuating the closure member at a predetermined third velocity a predetermined third number of cycles and the second configuration, actuating the closure member at a predetermined fourth velocity a predetermined fourth number of cycles and the second configuration, and actuating the closure member to the second configuration at a predetermined fifth velocity for a predetermined flushing period.

The present disclosure relates to diagnosing and locating fluid leakage within a pneumatic system (5) using a minimal amount of pressure sensors (55, 75, 89). In general, each branch (51, 71, 85) of a pneumatic system (5) includes an associated pressure sensor (55, 75, 89) and in accordance with how the pneumatic components (57, 59, 61, 77, 91, 93, 95) associated with the pneumatic branch (51, 71, 85) are toggled and monitored, leaks can be detected and located within the branch (51, 71, 85) using a minimal amount of pressure sensors (55, 75, 89). More specifically, pressure and pressure decay may be measured by the sensors (55, 75, 89) within a branch (51, 71, 85) while the pneumatic components (57, 59, 61, 77, 91, 93, 95) are in a particular configuration. The configuration is thereafter changed, and pressure and pressure decay are again measured by the sensors (55, 75, 89). The results of these two measurements may enable the pneumatic system (5) to derive the presence and location of a leak.

A pneumatically controlled flow booster includes a booster valve plug position sensor that enables control of the flow booster in a feedback loop, for example by a pneumatic valve positioner, thereby providing accurate, high speed, high flow control of both small and large actuator adjustments. Embodiments can accurately control a surge suppression valve over extended valve adjustment ranges and can fully open a surge suppression valve during a trip. The flow booster valve can include a spool and sleeve valve and/or a poppet valve. Embodiments provide bimodal flow boosting, whereby the output flow is less dependent on the valve plug position in a first position range, and more strongly dependent on the valve plug position in a second range.

A solenoid valve assembly has a valve body in which a spool is slidably mounted and operated by a solenoid having a coil. A manifold member has a plurality of flow paths for supplying and discharging pressurized fluid to and from ports of the solenoid valve assembly. An intermediate block is interposed between the valve body and the manifold member. The intermediate block has a plurality of through holes for connecting ports of the manifold member to ports on the valve body. At least one sensor is housed in the intermediate block for sensing at least one of pressure and flow in at least one of the through holes.

A controller (45) is provided with an elapse time measuring section (47A) that measures an elapse time (tx) elapsed since an initial use of an accumulator (29) based upon a reset signal from a reset switch (44), a number-of-operations measuring section (47B) that measures a number of operations of the accumulator (29), that is, a number (N) of boom lowering operations after a reset, based upon a detection signal from an accumulator side pressure sensor (39), a gas permeation amount estimating section (47C) that estimates an estimation gas permeation amount (Qloss) of the accumulator (29), a sealed gas pressure estimating section (47D) that finds an estimation sealed gas pressure (Pgs) of a gas chamber (29B) of the accumulator (29), and an accumulator degradation determining section (47E) that determines a degradation condition of the accumulator (29) and outputs the determination result.

A hydraulic valve assembly includes a first spool valve and a first selector valve for actuating a first hydraulic consumer port or a second hydraulic consumer port, and a second spool valve and a second selector valve for actuating a third hydraulic consumer port or a fourth hydraulic consumer port. A shut-off valve is arranged in a common pressure channel. A branch channel with first and second pressure branch channels branches off the pressure channel upstream of the shut-off valve. The first selector valve connects the first pressure branch channel to a first connection line in a first switching position and connects the second pressure branch channel to a second connection line in a second switching position. The second selector valve, in a first switching position, connects the first connection line to the control channel and, in a second switching position, connects the second connection line to the control channel.