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PAGE 50 — MAYCO ST-45HRM PUMP — OPERATION & PARTS MANUAL — REV. #4 (07/16/04)
ST-45 PUMP — MAINTENANCE (PUMP)
CYLINDER CUP REPLACEMENT PROCEDURE
1. Remove the two hydraulic hoses (Hopper Assy., Item 34)
connected to the remix motor. Plug the ports with fittings(not
provided) to prevent hydraulic hose leakage.
2. Remove the hopper discharge nipple (Hopper Interior
Assembly, Item 21) and loosen sleeve seal. Inspect and
replace if wear is excessive.
3. Remove the two tie rod nuts (Hopper Attachment, Item 19)
and the four eyebolt nuts (Hopper Attachment, Item 22)
securing the hopper to the pump frame.
4. Using an approved lifting device, remove the hopper
(Hopper Assy, Item 1) using extreme care not to damage
the hopper seal (Hopper Assy, Item 2).
5. Start the engine and turn on the pressure test switch (Figure
31). Cycle pump in reverse until hydraulic system obtains
maximum pressure, then turn pump and engine off.
Remove ignition key and disconnect battery.
Think safety! Check the hydraulic gauges (Figure 29) on
panel and make sure accumulator pressure reads zero.
One piston should be in the fully discharged position at the
end of the concrete cylinder.
CHANGING THE CONCRETE CYLINDER PISTON CUPS
The Rubber 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. Do not allow the
cups to become so worn that they begin to pass lubrication into
the material cylinders. If the liquid level of the lubrication box
becomes to low, the rubber cups will severely deform due to
excessive heat. Whenever replacement is due, both cylinder
cups should be replaced.
6. Remove the three 3/8 – 16 x 3” bolts (Lubrication Pistons
Assy, Item 20) from the piston. Remove the front faceplate
(Lubrication Pistons Assy, Item 19).
7. Install two the 3/8’ 16x3” bolts (Lubrication Pistons Assy,
Item 20) back into the piston – do not tighten. Use the two
bolts as leverage to remove the rubber piston cup
(Lubrication Pistons Assy, Item 17) and rear components.
8. Obtain two 3/8 16x7” full thread studs (these studs will be
used to assist in assembly alignment) insert the two studs
into the piston adapter P/N 16460. Coat the concrete
cylinder with grease.
9. The new “O” ring (Lubrication Pistons Assy, Item 12) must
now be modified. Using a sharp knife cut four oil passage
grooves into the ring. the grooves should be placed at a
distance of 90
o
apart. The cut should be a v-shaped design,
0.059” deep and 0.157” wide at the top.
10. Install the “O” Ring P/N 14407 around the oiler plate
(Lubrication Pistons Assy, Item 13). Install the plate into the
concrete cylinder utilizing the studs for alignment.
11. Install the felt holder (Lubrication Pistons Assy, Item 14)
over the oiler plate. Install felt ring (Lubrication Pistons Assy,
Item 15) into felt holder. Install the bronze ring (Lubrication
Pistons Assy, Item 16)
WARNING
ALWAYS relieve the accumulator circuit to ZERO pressure prior
to performing any maintenance on the pump.
NOTE
Before installing 3/8” bolt, coat the back
of bolt heads with silicon sealant.
Torque all three bolts equal at 55 ft.
lbs. each.
12. Using silicon sealant place a small bead of sealant
material on the front of the rubber piston cup and the rear of
the face plate. Install over alignment studs and into concrete
cylinders.
13. Insert one 3/8” 16x3” bolt into the open bolt hole, remove
the alignment studs one at a time and install the remaining
3/8” 16x3” bolts.
NOTE
Felt ring must be saturated with 30 wt.
oil prior to installation.