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PAGE 12 — C-30HD — PARTS & OPERATION MANUAL — REV. #4 (03/06/01)
C-30HD — HOW IT WORKS
The Mayco concrete pump has one main pumping piston
which is valved by means of two ball checks. (A inlet, and B
outlet.)
The secondary piston is used as a compensator piston to
smooth out the pulsations of a single piston action. Note: The
compensator will not start operating until material is pumped
into the line and back pressure develops.
The compensator spring, which is installed on the
compensator piston rod, deflects with each piston stroke. This
“spring cushion”, in conjunction with the cam profile, produces
and uninterrupted smooth flow of material under average
pumping conditions.
An automatic, centrifugal clutch is installed to engage and
disengage the pumping action without stopping or starting the
engine. The centrifugal clutch is set at 1100 R.P.M. release.
The engine idle speed is approximately 750 R.P.M.; therefore,
the clutch is completely disengaged at idle. The throttle settings
while pumping should always maintain an engine R.P.M. high
enough to prevent the clutch from slipping and burning the
clutch lining.
The return spring which is installed on the rocker arm, is
installed to eliminate shock and stress between the cam roller
and the cam weldment when the pump is in operation. If the
return spring is removed or replaced for any reason, maintain
the backing plate dimension of 3” as shown on Figure 3, to
produce the proper pre-loading of the spring for a smooth
performance.
Figure 1- The pumping cylinder retracts drawing the material
past the ball (A) and filling the cylinder. The compensator piston
is pumping the material out to the nozzle and causing ball (B)
to seat preventing the material from returning to the pumping
cylinder intake.
Figure 2- The pumping piston is forcing the material past ball
(B) and out to the nozzle, also seating ball A so that the material
will not flow back to the hopper. This action also fills the
compensating piston for the next stroke.
Figure 3- Shows the relationship between the return spring,
the compensator spring and the rocker arm to maintain a
smooth performance. Do not tighten the bolt (Item 1)
completely, the rod end must be able to move.