Roland ep-5 Service Manual download pdf (Page 7)

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2. Function

1 2

5 6

The P5 operates on a force balance principal. Force is originated by the

signal pressure transmitted through a diaphragm on to the balance

arm. The opposing force is achieved through the feedback spring and

is proportional to the position of the lower arm. The lower arm posi-

tion is determined by the position of the cam which is secured to the

spindle and connected to the actuator shaft thus providing the feed-

back from the actuator/valve. When these two forces are equal, the

balance arm and the spool in the pilot valve are in a neutral position

-the complete unit is in a balanced position. Air is supplied to the pilot

valve through port S, and controls the air flow through ports C1 and

Assume an equilibrium position.

An increased control pressure will deflect the diaphragm 1 down,

compressing the feedback spring 3. The balance arm 2 moves the spool

7 in the pilot valve 8 furnishing supply air to the actuator, while at the

same time air is exhausted from actuator and is vented to atmosphere

through the pilot valve and the OUT port .

With the increased supply air, the actuator rotates (or moves linearly)

moving the positioner spindle 6. The spindle and cam 5 rotate, forcing

the lower arm 4 upwards compressing the feedback spring 3. This

motion will continue until the two forces are equal and the unit is in an

equilibrium position.

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Roland ep-5 Service Manual Page 7