301 F (B) - Hydraulic Valves II

Question 1

How are Directional Control Valves Classified?

Answer 1

Type (Rotary, Poppet, Sliding Spool)
Condition and Number of Paths
Number of Positions
Actuation Methods
Detents

Question 2

What is the common material used for construction of Directional Control Valve housings?

Answer 2

Fine Grain Cast Iron or Aluminum

Question 3

What is the simplest of all Flow/Directional Control Valves?

Answer 3

Poppet Valve

Question 4

Explain some features of a Sliding Spool Valve

Answer 4

Minimum Leakage

Metering Notches for Feathering

Question 5

Explain some advantages/disadvantages of Rotary spool valves.

Answer 5

Higher amount of leakage

Used for lower pressures and flow rates

Question 6

What is a Diverter Valve?

Answer 6

A Two Position, Three Way Directional Control Valve

Question 7

What is a Directional Control Valve Float position?

Answer 7

Where a Double Acting Cylinder has its base and rod ends both supplied to tank. Allowing the cylinder to float and be used in a variety of uses.

Question 8

When an open centre directional control valve is being used, what type of pump is being used within this system?

Answer 8

Fixed Displacement Pumps

Question 9

What is a series passageway?

Answer 9

The passageway through Open Centre Open Port directional control valves

Question 10

What are 3 ways that directional control valves are actuated?

Answer 10

Mechanical through Levers
Pilot Operated by Hydraulic or Air
Electronically through Solenoids

Question 11

What does a pilot operated directional control valve require to be effective?

Answer 11

A Tandem pilot pressure pump will be used.

Question 12

What is one disadvantage of using electrical actuators for directional control valves?

Answer 12

There is no feathering possible.

Question 13

How is a detent on a directional control valve achieved?

Answer 13

Through the use of spring loaded balls to latch position of the spool.

Question 14

What types of pressure control valves can be mounted inside a directional control valve?

Answer 14

Relief
Load Check
Anti Cavitation
Flow Compensator

Question 15

What is a load check valve?

Answer 15

Check ball mounted in the pump supply port of a directional control valve, preventing loads from causing a higher pressure overrunning pump.

Question 16

What is an Anti Cavitation Valve?

Answer 16

Check ball on return line of actuators, used to prevent air from being sucked in when a heavy load pulls the piston down faster than the pump can fill the rod end.
This acts like a regeneration valve.

Question 17

What is a Flow Compensator Valve?

Answer 17

A Pressure Compensator valve installed in the directional control valve with a checkball installed on the outlet of the work ports. This ensures constant pressure drop in and out of the Controls.

Question 18

What are two styles of Control Valve assemblies with multiple controls?

Answer 18

Unibody style, cast as one housing.

Valve Stacks, stacked individual valve assemblies.