Hydraulic Valves Flashcards
Pressure relief valves can either be maximum pressure or ________?
Unloading valves
What are the two basic designed of maximum pressure release valves?
Direct acting (simple relief)
Piloted operated relief (two stage or compound relief valves
Where would you find direct acting relief valve?
Can handle small flows or where accurate control of pressure is not important.
What are the three things relief valves perform?
Cracking pressure
Full flow pressure
Pressure override
A maximum pressure relief valves uses 33.3% more energy to maintain full flow through it. Which valve will only use 5 % override?
Pilot operated relief valve
Trouble shooting pilot operated pressure control valves
What is the purpose of a sequencing valve?
To control the order of operation
Problems and remedies for sequence valve.
Why is a counter balance used?
Used to control vertical cylinders that are loaded so they do not fall freely due to gravity. Identical to sequence valves except the internal drain had replaced the sequence valves external drain.
Counter balance faults and remedies
Why are brake valves needed?
They prevent overspeeding when an overrunning load is applied
They prevent excessive build up when decelerating or stoping a load.
Stack valves are bolted together in a stack and can control one or more actuators. What is the advantage of stacking valves?
More compact and less lines connecting the system together. Less chance for leaks.
Why is used to seal the stacks together?
O rings
What is the order of you should stack “stack valves”?
- Relief valve be placed closed to the sun plate so it can protect the whole system.
- flow controls are placed between pilot to open check valves and the actuator to avoid chatter.
- the directional control is placed at the top of the stack to supply pressure and flow controls.
How is the stack valve supplied and drained?
Through the sub plate or manifold. Always at the bottom.
The four ISO sizes for stack valves are:
What is the advantage of a cartridge valve?
Very compact design, mounted to a manifold block. They are very popular because of there compact design and reduction of external hoses which are possible leak points.
What are the two basic types of cartridge valves?
Screw in (30-35 gpa)
Slip in (large flow over 30 gpa
Can you have multiple flow paths with slip in cartridges?
Yes you can select different sizes depending on the amount of flow needed for the required amount of flow.
How is a slip in cartridge valve indicated if it is used as a flow control?
A triangle on the poppet
In a slip in cartridge what is the designation for the pilot port?
Ap
Which of the slip in or screw in cartridge valves can be re built?
Slip in
What is the advantage of a proportional valve?
It can be moved to an infinite number of positions within its working rang by the varying electrical input
What are the advantages of proportional valves?
- Simple design
- great accuracy
- simple circuit designs
- ideal for applications that can benefit from electronic control but do not require high accuracy
- more rugged and dirt tolerant the. Servo valves
