January 2001
Installation, Operation and Maintenance Manual
PBC-01102001 Rev. A
4
Section 1: Introduction
Introduction
Section: 1 Introduction
The poppet block is the heart of most Shafer control systems. A double three-way, manual
and pilot actuated, control valve is designed to provide selective directional operation of
Shafer actuators. The poppet block control may direct power gas to a set of gas/hydraulic
tanks (generating hydraulic pressure for powering valve actuators), or it may direct central
hydraulic system pressure directly into a valve actuator. It is engineered to provide reliable
and durable operation and toleration of contaminates in the power source.
1.1 Basic Construction
The poppet block control consists of a double three-way ported valve body containing
two sets of inexpensive, easily replaced nylon poppets to provide tight sealing, poppet
springs, push pins, power and pilot lters, a manual lever assembly and pilot pistons for
remote operation.
NOTE:
For low pressure applications, 350 psi or less, the power poppets item (2) in Figure 1 are
steel backed Neoprene poppets. The exhaust poppets item (3) in Figure 1 are nylon.
1.2 Operation
Spring compression (1) and power gas force the power poppets (2) on their respective
seats and simultaneously hold exhaust poppets (3) in the open position via interconnecting
poppet pins. Tank porting is open to exhaust. The exhaust port is equipped with a check
valve (4) to prevent atmosphere from entering the poppet block assembly.
Figure 1 Neutral Position
TANK “A”
POWER PILOT
EXHAUST OR
RETURN OIL
TANK “B”
1
2
3
4
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