29EATON 620 Mobile Open Circuit Piston Pump Service Manual E-PUPI-TS018-E2 November 2017
Inspection, repair and
part replacement
Inspection
Rotating group parts
1. Inspect cylinder block face for wear, scratches and/or
erosion. If cylinder block condition is questionable, replace
the entire rotating group.
2. Remove the pistons, shoe retainer, and pivot from piston
block. The piston block assembly does not need to be
disassembled unless the internal pins or springs are
damaged.
3. Check each cylinder block bore for excessive wear. Use the
piston and shoe S/A for this purpose. The pistons should
be a very close fit and slide in and out of the cylinder block
bores. No binding can be tolerated. If binding occurs,
clean the cylinder block and pistons. Lubricate the cylinder
block bores with clean oil and try again. Even minor
contamination of the fluid may cause a piston to freeze up
in a cylinder bore.
4. Inspect each of the nine piston and shoe subassemblies
for maximum end play of 0.08 mm between the piston
and shoe.
5. Inspect shoe retainer and pivot for wear and/or scratches.
If condition is questionable, replace entire rotating group.
Note: Do not lap the face of cylinder block assembly
Piston S/A Tolerances This dimension must be
maintained on all nine
shoes within 0.03 mm
Shoe face rides on swash
plate. Shoe must swivel
smoothly on ball.
Before Inspection of parts, clean with a solvent
that is compatible with system fluid.
±0.03mm
Between Piston Shoes (9)
Movement up to 0.08mm
Shoe
Piston
Retainer Plate
Piston Block
Piston
Pivot
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