190301fB Flashcards
The most commonly used type of directional control valve used in heavy equipment
hydraulic systems is the:
sliding spool type.
A diverter valve is a __________ way, __________ position directional control
valve.
three way, two position
In the float position, the directional control valve connects the work ports to the
_______________________. The effect on the actuator is
reservoir./ that it will follow the contours of the ground
because it is not hydrostatically held in position.
A directional control valve with a hold position will:
have its work ports closed in the neutral position.
Closed centre directional control valves that are supplied by fixed displacement
pumps use a relief valve to limit maximum system pressure. T/F
false;
A pressure regulating pilot controller provides accurate directional control valve
movement because it regulates:
pilot pressure to the directional control valve.
The main disadvantage of electrical directional control valve actuation is that it does
not allow feathering of the directional control valve. T/F
true
The component that prevents a suspended load from dropping momentarily when the
directional control valve is moved from the hold to the raise position is called:
a load check valve.
The function of an anti-cavitation check valve is to _________________
prevent a void from forming in
the actuator
State two (2) advantages that directional control valve stacks have over unibody valves.
a) Control valves for additional functions can be easily added to the stack.
b) An individual valve can be replaced when it is damaged, rather than replacing the
whole valve assembly.
The passage that carries pump oil flow through an open centre directional control
valve when it is in neutral is called the __________ passageway.
series
When two functions of an open centre, series-parallel directional control valve are
actuated at the same time, how will the actuators react?
The actuator with the lightest load will operate first.
State three (3) methods of connecting an auxiliary directional control valve into an open centre hydraulic system.
a) Use a diverter valve.
b) Use a power beyond sleeve.
c) Use a flow divider.
When a diverter valve is used to connect an auxiliary directional control valve into an
open centre hydraulic system, the main and auxiliary valve can be operated
simultaneously. T/F
false;
Auxiliary closed centre directional control valves can be connected into an existing
closed centre hydraulic system by connecting the auxiliary valve in:
parallel.
