Hydraulic Valves Part A/B Flashcards
What are the 2 basic designs of a maximum pressure relief valve?
- Direct acting relief (simple relief valve)
2. Piloted operated relief (two stage relief or compound relief valve)
What are some main characteristics of a pressure reducing valve? And what is the purpose of this valve?
- normally open
- pioleted from outlet port
- external drain for variable spring
- reverse flow bypass with flow coming from the cylinder.
The purpose of this valve is to reduce the pressure to a part of the system that requires less pressure.
What are some characteristics of a sequence valve?
What is the purpose of a sequence valve?
- order of operations
- normally closed
- externally drained
The purpose of this valve is to block the flow of fluid to the second actuator in a sequence until the first one has completed its job.
What are some characteristics of a counter balance valve? And what is it’s purpose?
- normally closed
- piloted from the inlet side (can sometimes be piloted from an external inlet.
- reverse flow bypass
They control vertical cylinders that are loaded so they do not fall freely from gravity
What are the 2 reasons you would use a brake valve on a hydraulic motor?
They prevent over speeding when an overrunning load is applied to a hydraulic motor.
They prevent excess pressure buildup when decelerating or stoping a load.
Which proportional DCV control loop provides the most accurate throttling in a high flow hydraulic application?
Closed outer loop
Pressure override of a relief is?
Pure difference between the cracking pressure and full flow pressures
What pilot line prevents the motor from running away on a brake valve?
External pilot
What would the pilot spring be set to in an internally piloted counterbalance valve?
The load pressure plus 10%
A bleed off circuit is usually used for?
For metering in to increase system efficiency
Stack valves are supplied and drained through a?
Sub plate
