A control mechanism for a stepless transmission is a control mechanism connected to a manipulation lever in a stepless transmission and disposed outside a housing of the transmission. The control mechanism includes: a) a piston rod connected to the manipulation lever; b) a piston provided on the piston rod coaxially with the piston rod; c) a cylinder case provided with a cylinder adapted to house the piston rod and the piston such that the piston rod and the piston are displaceable in an axial direction, the piston and the cylinder forming a first fluid chamber to be supplied with a hydraulic fluid for withdrawing the piston rod from the cylinder and a second fluid chamber to be supplied with the hydraulic fluid for introducing the piston rod into the cylinder; d) a spring adapted to bias the manipulation lever in a neutral direction coaxially with the piston rod; e) a proportional pressure control valve adapted to selectively supply the hydraulic fluid to the first fluid chamber or the second fluid chamber, the proportional pressure control valves being mounted to the cylinder case; and f) a pivot shaft adapted to support the cylinder case oscillatably with respect to the housing.

A pump system is disclosed for use with a fuel system of an engine. The pump system may have a first pump with a first end, a second end, a reservoir located at the second end, and at least one pump mechanism configured to receive fluid from the reservoir. The pump system may also have a second pump mounted to the first pump at the second end and having at least one pump mechanism configured to discharge fluid into the reservoir of the first pump. The pump system may further have a mechanical input operatively connected to the at least one pump mechanism of each of the first and second pumps.

A hydraulic pump assembly having a main pump, a charge pump and an auxiliary pump driven by a single shaft is provided. A pair of hydraulic porting members cooperates to feed and distribute hydraulic fluid between the three pump units, and a single inlet may be used to provide hydraulic fluid to the charge pump and the auxiliary pump.

A system and method of producing fluid from a wellbore by pressurizing the fluid and then directing the pressurized fluid to a centrifugal pump. Pressurizing the fluid compresses gas or vapor within the fluid, thereby decreasing the volume ratio of the gas or vapor within the fluid, which in turn increases operating efficiency of the centrifugal pump. A positive displacement pump, such as a gerotor pump, is used for pressurizing the fluid prior to sending it to the centrifugal pump.

A submersible pumping system has an electric motor, a rotary hydraulic pump driven by the electric motor, and a linear hydraulic pump that is configured to move a production fluid. The rotary hydraulic pump produces a pressurized working fluid that drives the linear hydraulic pump. In another aspect, a method is disclosed for controlling the temperature of an electric motor within a submersible pumping system disposed in a wellbore. The method includes the steps of circulating motor lubricant through a hydraulically driven production pump to reduce the temperature of the motor lubricant.

A pump-regulator combination includes first and second pumps, a control valve, first orifice, and pilot valve. The first pump is configured to pump fluid from a tank to a first point. The control valve is configured to control pressure and/or delivery flow at the first point by adjusting a displacement volume of the first pump. The second pump is configured to pump fluid from the tank to a second point, through the first orifice, and back to the tank. A highest load pressure of the actuator is connected to a third point. The pilot valve includes an adjustable second orifice connected to the third point, via a fourth point, and the tank to pass fluid from the actuator to the tank. A pressure at the second point acts to close the second orifice. A pressure of the fourth point acts to adjust the control valve.

A swash plate type liquid-pressure rotating device includes a movement restricting mechanism configured to restrict a movement of a spherical bushing relative to a rotating shaft toward a first side in an axial direction. The movement restricting mechanism is a restricting member such that a portion of the spherical bushing which portion is located at the first side in the axial direction contacts the restricting member. The swash plate type liquid-pressure rotating device further includes: a stopper attached to the rotating shaft; and a gap adjusting member. The gap adjusting member is inserted into a gap G3 formed between the stopper and the bearing when the spherical bushing, the retainer plate, the shoe, and the swash plate tightly contact one another in the axial direction. The gap adjusting member restricts a movement of the rotating shaft relative to the casing toward the first side in the axial direction.

A cementing equipment and a control method. The cementing equipment includes a centrifugal pump, a plunger pump, and a lubrication system. The lubrication system includes: a lubricating oil pump, including a first lubricating oil outlet and a second lubricating oil outlet; a first distribution valve, including a first inlet, at least one first outlet, and a third outlet, where the first outlet is communicated with a packing lubricating end of the centrifugal pump, the first lubricating oil outlet is communicated with the first inlet; and a second distribution valve, including a second inlet and at least one second outlet, where the second outlet is communicated with a packing lubricating end of the plunger pump, the second lubricating oil outlet is communicated with the second inlet or the second lubricating oil outlet is communicated with the first inlet, and the second inlet is communicated with the third outlet.

The present patent of invention refers to a hydraulic unit (U) that uses at least one rolling weight (8) having radial movement, connected to a drive shaft (3) moved by at least one servomotor (1), in order to exert the force, favored by the action of gravity, on the hydraulic pistons (11) of sequential pumps positioned on a circular track (12), which force can be enhanced by the activation of a pneumatic cylinder (13), the speed of the servomotor (1) or the quantity of rolling weights (8), thereby obtaining volumes of pressurized hydraulic oil, using small/low-power electric motors.

A high and low-pressure integrated air pump includes a single housing including an air inlet and an air outlet. A high-pressure pump is disposed within the housing and in fluid communication with the air inlet, and uses a first outlet passage to discharge to the air outlet. A low-pressure pump is also disposed within the housing and in fluid communication with the air inlet, and uses a second outlet passage to discharge to the air outlet.