Multiquip ST70 - Manual (Page 89)

ST-70 — PARTS & OPERATION MANUAL — REV. #4 (05/29/07) — PAGE 89
ST-70 — SERVICE INFORMATION
Changing the wear plate and ring
Due to the swinging motion of the Nun-plate and the abrasive
nature of concrete it is normal for the cutting ring to wear on the
side that shears through the concrete inside the hopper. If the
wear ring and wear plate do not fully seat against each other.
The concrete slurry will pump into the hopper. This condition
can be easily observed by the sudden change of the level of
concrete inside the hopper during each stroke.
Warning! Danger of Amputation!
The Mayco pump is equipped with a nitrogen accumulator,
which stores hydraulic energy. You will be required to put your
hand in the concrete cylinders or near the suttle. You are at
extreme risk if the engine is running or if pressure is in the
hydraulic system. Prior to working on the pump, stop the engine
by turning off the ignition switch, remove starter key, place a “Do
not operate” tag over the switch and disconnect the battery. The
pressure reading on the accumulator pressure gauge must read
zero. Always relieve the accumulator circuit to zero pressure
prior to working on the pump.
Replacement procedure
Step 1: Remove and plug the two hydraulic hoses connected
to the remix motor P/N 25425.
Step 2: Remove the hopper discharge nipple P/N 25836 and
loosen sleeve seal P/N 16819 inspect and replace if
wear is excessive.
Step 3: Remove the two tie rod nuts P/N 16166 and the four
eyebolts nuts P/N 452558.
Step 4: With a lifting devise, remove hopper P/N 25174 use
extreme care nut to damage the hopper seal P/N 16184.
Step 5: Remove the four 5/8”-11 1 ½ “ bolts that hold the suttle
tube to the nun-plate and remove suttle tube. The
energizer ring and wear ring will normally have
concrete contamination holding them in position. It will
be required to chip some of the concrete loose to better
expose the energizer ring. Using two small pry bars
remove the energizer ring P/N 16816-1, insert ring
P/N 16816-2 and wear ring P/N 16171.
Step 6: Clean out all concrete build up in and around the nun-
plate area with a wire brush.
Step 7: Inspect the wear components for indications of wear.
Note: it is typical that the wear plate P/N 25841 will
have two times the service life compared to the cutting
ring. The wear plate has two wear surfaces. If it
becomes necessary to replace, the plate can be
reversed to the opposite side to expose a new flat
surface. To replace or reverse the plate, remove the
five allen head counter suck bolts. Next remove the
two cylinder “O” rings and clean the entire back
surface.
Step 8: Wear plate installation: install the two cylinder “O” rings
P/N 16174. Using silicon sealant, coat the
circumference of the concrete cylinders, wear plate
back and around the five bolt holes. Next, install the
wear plate and the five bolts. Note: the bolts must all be
equally snugged and tightened to 100 foot pounds
each.
Step 9: Wear ring installation: Install the wear ring P/N 16171
into the nun plate. Install the insert ring P/N 16812-2
inside of the rubber energizer ring P/N 16816-1. Install
the energizer ring assembly into the nun-plate.
After installing the above mentioned components the machine
can be re-assembled by reversing steps 1 through 5.