a device placed in the passageway of a moving fluid in order to restrict its flow rate or to alter its pressure in the channel. Hydraulic throttles may be of the constant (nonregulating) or the variable (regulating) types. Among the constant types are capillary, throttle bushing, washer, and washer-packet throttles; the variable types include those with slide-valve pairs, throttling valve nozzles, and throttling screw-type nozzles. Depending on the fluid flow condition in the working channel (laminar or turbulent), a hydraulic throttle may be linear (the pressure drop is proportional to the fluid flow rate) or quadratic (the pressure drop is proportional to the square of the fluid flow rate).
Hydraulic throttles are used to vary the flow rate of a pressure fluid and also to regulate the speed of a machine’s actuating members. They also produce necessary pressure drops of the pressure fluid in hydraulic systems and control hydraulic actuators in hydraulic servomechanisms.
V. A. KHOKHLOV