6 HP Pump G Series • MLP-28/46S
7
Maintenance (continued from page 3)
Disconnect pump from system and remove to a clean, well lit work bench with access to vice, tools, seal
kits and spares. All parts removed for inspection should be washed in suitable de-greasing agent such as
Blue Gold or equivalent. Inspect all moving parts for wear or scratches. Damaged parts should be
replaced. It is recommended that all seals and o-rings are replaced. Specially packed seal kits are
available. Seal Kit Part Numbers are:
Air
Drive
P/N
51215
Air Cycling Valve
P/N 51396
GW-35 Hydraulic Section
P/N 27616-35
GW-60 Hydraulic Section
P/N 27616-60
GW-100 Hydraulic Section
P/N 27616-100
GSF-35 Hydraulic Section
P/N 29670-35
GSF-60 Hydraulic Section
P/N 29670-60
GSF-100 Hydraulic Section
P/N 29670-100
See separate parts list drawings for models DGF, DGSF, DGSTV-35, -60, -100 and GWD-12, GSFD-12,
DGFD-12, DGSFD-12 and DGSTVD-12.
Air Drive Section
The air drive section can be dismantled for inspection by removing the (5) tie rods, (2) tube assemblies
(connecting the two ends of the drive), the end cap, the air cycling valve body and air barrel. The air
piston will slide off the piston rod after removing the cotter pin and nut. Carefully inspect pilot valve stem
seal on both end caps. Do not try to reuse retaining ring if removed. Install new retaining ring by inverting
the pilot valve as a mandrel to center the retaining ring. Then lightly hammer the pilot valve against the
retaining ring. The rubber seat on the valve will then force the 'legs' of the retaining ring to deflect equally.
The air piston and air barrel should be re-lubricated on assembly with Haskel silicone grease P/N 50866.
Torque the tie bolt nuts evenly to 21 - 25 ft-Ibs. The internal components of the air cycling valve should be
removed from the retaining plate end. The two flat bumpers, P/N 50008, should be inspected for wear.
Prior to re-assembly Haskel silicone grease, P/N 50866, should be applied to all components for ease of
reassembly and continuous lubrication during operation. Torque air valve retaining screws to 60 - 70 in-
Ibs.
NOTE: The 568030-2 rings on either end of the 17634 sleeve are installed as follows: Install inner
bumper on bottom of bore in valve body. Lay sleeve end inner o-ring on inner bumper. With (2) middle o-
rings installed on sleeve, slide sleeve in against inner o-ring and bumper. Then to “seat” fourth (outer) o-
ring evenly into the groove on the end of sleeve, use bare cab/pilot piston assembly as a seating tool.
Hydraulic Section
The hydraulic section can be dismantled for inspection by removing the (4) hydraulic barrel connecting
bolts and then extracting the barrel. The piston rod bearings and packing can easily be withdrawn once
the piston head is removed. Note that the chamfer on the bronze seal faces away from the seal. When re-
assembling the piston head, insert a 1/4” O.D. tube (17687 tool) through the head and use to hold the
check valve ball in position while screwing the head onto the rod if the pump is horizontal. No tool is
needed if the pump is vertical. Lap inlet check valve and inspect retaining spring. Ensure tip ends of
spring do not protrude in or out after assembly. Torque the hydraulic barrel bolts evenly to 21 - 25 ft-lbs.
0.032” stainless steel locking wire is used to prevent the hydraulic barrel and the hydraulic end cap
working loose through vibration. Replace with new wire when reassembling.
