A fluid end assembly comprising a housing having multiple conduits formed therein. A tubular sleeve is installed within one of the conduits and is configured to house a plurality of packing seals. A seal is installed within a groove formed in the walls of the housing surrounding the tubular sleeve such that the seal engages an outer surface of the tubular sleeve.

A valve unit (V) has a valve housing (50) that includes a supply oil passage (55) configured to receive operating oil from a hydraulic pump, and a pressure adjustment valve (Va) configured to adjust the pressure of the supply oil passage (55). The pressure adjustment valve (Va) includes a pressure adjustment valve body (61) configured to open and close the supply oil passage (55), a compression coil spring (62) that keeps the pressure adjustment valve body (61) at a closed position when the pressure of the supply oil passage (55) is smaller than a set value and allows the pressure adjustment valve body (61) to open when the pressure of the supply oil passage (55) is not smaller than the set value, and a restriction member (63) configured to, when the pressure adjustment valve body (61) becomes open against the urging force of the spring (62) in response to a pressure of the operating oil, abut against the pressure adjustment valve body (61) to restrict movement of the pressure adjustment valve body (61).

Apparatus and method contemplating a high pressure fluid end assembly having a body defining a body bore and defining a groove in the body intersecting the body bore. A closure is joined to the body and forms a sealing surface. A seal is mounted to the body in the groove and configured to extend from the groove beyond the body bore to seal against the sealing surface formed by the closure.

Apparatus and method contemplating a high pressure fluid end assembly having a body defining a body bore and defining a groove in the body intersecting the body bore. A closure is joined to the body and forms a sealing surface. A seal is mounted to the body in the groove and configured to extend from the groove beyond the body bore to seal against the sealing surface formed by the closure.

A method for controlling a hydraulic actuator (2) of a system (1) by means of a valve having a valve element is described. A position of the valve element determines a pressure supplied to a hydraulic actuator (2). In such a method a variable dead band should be minimized. To this end a start position of the valve element is preadjusted as a function of at least one parameter outside the hydraulic actuator (2).

A method for controlling a hydraulic actuator (2) of a system (1) by means of a valve having a valve element is described. A position of the valve element determines a pressure supplied to a hydraulic actuator (2). In such a method a variable dead band should be minimized. To this end a start position of the valve element is preadjusted as a function of at least one parameter outside the hydraulic actuator (2).

This clutch control device includes an engine (13), a transmission (21), a clutch device (26) configured to connect and disconnect motive power transmission between the engine (13) and the transmission (21), a clutch actuator (50) configured to drive the clutch device (26) and change a clutch capacity, a hydraulic circuit (63) provided between the clutch device (26) and the clutch actuator (50), an air bleeding device (64) configured to perform air bleeding of the hydraulic circuit (63), a control unit (60) configured to calculate a control target value of the clutch capacity, a control mode changeover switch (59) configured to enable a control mode of the control unit (60) to be switched to an air bleeding mode, and an air bleeding switch (65) configured to enable a hydraulic pressure of the hydraulic circuit (63) to increase in the air bleeding mode.

An easily installed and quick reacting in-line clutch engagement control device for hydraulically actuated power transmission friction clutches. The device allows a simple way to quickly and precisely limit a friction clutch's initial torque capacity to an easily adjustable pre-set level.

Apparatus and method contemplating a high pressure fluid end assembly having a body defining a body bore and defining a recess in the body intersecting the body bore. A closure is joined to the body and forms a sealing surface. A seal is mounted to the body in the recess and configured to extend from the recess beyond the body bore to seal against the sealing surface formed by the closure.

Apparatus and method contemplating a high pressure fluid end assembly having a body defining a body bore and defining a recess in the body intersecting the body bore. A closure is joined to the body and forms a sealing surface. A seal is mounted to the body in the recess and configured to extend from the recess beyond the body bore to seal against the sealing surface formed by the closure.