Module 7 Flashcards
a valve that limits and regulates the pressure and controls the flow rates of fluid in a hydraulic system
Pressure-control valve
a valve that protects a hydraulic system against excess pressure by gradually opening to relieve pressure
Pressure-relief valve
a valve used when it is necessary to have one cylinder actuated either before or after another
Sequence valve
a valve used to support a hoisted load or to prevent uncontrolled fall
Counterbalance valve
a valve used to limit the pressure in one part of the system to below that of the main part of the system
Pressure-reducing valve
Do pressure-control valves have any partially open positions between fully closed and fully open?
Yes
Are pressure-relief valves normally open or normally closed?
Normally closed
Name the two general categories into which all relief valves can be divided.
Direct-acting, Pilot-operated
Direct-acting poppet relief valves are held in the normally closed position by a(n) _____.
Spring
The difference between the set (maximum) pressure point and the cracking-pressure point for a relief valve is called the _____.
Operating differential pressure
When a relief valve is controlled from a remote point, is the main valve usually a single-stage or a two-stage valve?
Two-stage
What type of valves are used when it is necessary to have one cylinder actuated either before or after another?
Sequence
An adjustable back-pressure or braking valve is usually called a(n) _____ valve.
Counterbalance
A valve that is similar to a counterbalance valve, but which offers less resistance to return flow, is a(n) _____.
Holding
Unloading valves are commonly used in hydraulic systems that have more than one _____.
Pump
Is a pressure-reducing valve used to limit the pressure in one part of the system only or in the entire system?
One part
Hydraulic shock in a system is usually controlled by a(n) _____.
Shock suppressor
The speed at which an actuator moves is determined by the amount of _____.
Fluid flow
Name the three ways in which a flow-control valve can operate.
Meter in, Meter out, Bleedoff
A pressure-compensation valve is controlled by pressure on the _____ side of the valve.
Downstream
Temperature-compensation valves are usually equipped with an element that _____ as the temperature rises.
Expands
A pressure-reducing valve is a normally _____ valve.
a. closed three-way
b. closed two-way
c. open three-way
d. open two-way
d. Open two-way
What is another term for the maximum pressure of a poppet relief valve?
a. Cracking pressure
b. Flow capacity
c. Operating differential pressure
c. Set pressure
d. Set pressure
What is the pressure at the discharge (outlet) of a sequence valve?
a. cracking pressure
b. Line pressure
c. Negative pressure
d. Set pressure
b. Line pressure
A counterbalance valve is usually constructed as a
a. double poppet
b. double spool
c. single poppet
d. single spool
a. Double poppet
Unloading valves are usually made for _____ operation.
a. direct-acting
b. manual
c. pilot
d. presssure
c. Pilot
Pressure-reducing valves limit pressure
a. at the pump
b. in one part of the system
c. in two separate parts of the system
d. throughout the entire system
b. In one part of the system
Hydraulic shock in a system is controlled by a(n)
a. adjustable orifice
b. counterbalance valve
c. shock suppressor
d. unloading valve
c. Shock suppressor
The speed of a hydraulic actuator is controlled by what characteristic of the hydraulic system?
a. Flow
b. Pressure
c. Temperature
d. Viscosity
a. Flow
A flow-control valve can be positioned to operate in all of the following ways except
a. bleedoff
b. counterbalance
c. meter in
d. meter out
b. Counterbalance
A pressure-compensation valve senses pressure at the
a. downstream valve outlet
b. pump
c. reservoir
d. valve inlet
a. Downstream valve outlet
