MULTIQUIP LS450 - Wear Components and Pressure; Checking Accumulator Bladder Pressure; Wear Plate and Cutting Ring

PAGE 50 — MAYCO LS450 CONCRETE PUMP • OPERATION MANUAL — REV. #2 (02/23/21)
MAINTENANCE
Checking Accumulator Bladder Pressure
The normal accumulator pre-charge pressure should
be approximately 1,100 psi. To check the accumulator
pressure:
1. Start the engine and stroke the pump. The accumulator
pressure gauge (Figure 57) should read 1,750 psi.
Figure 57. Accumulator Pressure Gauge
2. To determine the actual accumulator pressure, stop
the engine and observe the pressure gauge. As
the pressure reading slowly decreases, it will reach
a point where there will be a sudden drop in the
pressure. The pressure reading should be taken just
prior to this sudden drop. If you do not read 1,100 psi,
the accumulator may require charging or bladder
replacement.
WEAR PLATE AND CUTTING RING
Due to the abrasive nature of concrete, it is normal for the
cutting ring to wear on its sides as it shears through the
concrete inside the hopper. The metal-to-metal friction and
the abrasiveness of the concrete will cause extreme wear
and reduced sealing capability between the cutting ring
and wear plate.
If the two components do not properly seat against each
other, slurry will pump into the hopper rather than out of
the discharge line. See Figure 58. This condition can be
easily observed:
 The level of concrete inside the hopper changes
suddenly during each pumping stroke.
 Concrete slurry squirts into the air from the hopper
(volcano effect).
0
ACCUMULATOR
PRESSURE
500
1000 2000
3000
2500
1500
 The output volume at the end of the delivery line
decreases in pressure.
 Frequent, unusual material packs in the shuttle tube.
Figure 58. Wear Plate and Cutting Ring
It is important that the wear components be inspected
weekly for proper sealing. Failure to inspect will eventually
cause severe damage to the nun plate and material
cylinders. Visually inspect the wear plate and cutting ring
to ensure surfaces are sealed against each other.
If a deep groove or a wide space has developed on the
sealing surfaces, it is time for replacement. Due to the
motion of the shuttle tube, the cutting ring experiences
a quicker rate of wear as opposed to the wear plate. The
wear ring typically requires replacement two times per wear
plate (2 to 1). When replacing the wear ring, also replace
the rubber energizer ring.
Changing the Concrete Cylinder Piston Cups
The urethane piston cups will occasionally require
replacement depending on the following factors.
 The fluid level and cleanliness of the lubrication box.
 The size and type of aggregate.
 The type of concrete being pumped.
It is time to replace the cups when increasingly large
particles of sand and cement pass into the lubrication box.
GOOD SEAL LEAKING
SHUTTLE TUBE
(INSIDE HOPPER)
RUBBER
ENERGIZER
WEAR
PLATE
CUTTING
RING