Manitowoc Grove RT770E, Service Maintenance Manual

Page: 120 / 357

HYDRAULIC SYSTEM RT770E
2-80 Published 11/26/2014, Control # 447-05
Assembly
NOTE: Do not use any sharp objects to install seals. Make
sure to install all seals with sealing lips facing the
correct direction.
1. Install the seals on the outside of the piston and the back
up rings and O-ring in the inside of the piston.
2. install the O-ring and backup ring on the outside of the
head and the wear rings, buffer seal, rod seal and wiper
ring in the inside of the head.
3. Lubricate the head seals with clean light oil and slide the
head onto the rod. Tap on with a rubber mallet to engage
the seals.
4. Push the head half way down the length of the rod.
5. Install the spacer on the rod.
6. Lubricate the piston seals with a clean light oil and
thread the piston clockwise onto the rod with the
spanner wrench until it bottoms out.
7. Install the setscrew with a 3/16 inch allen wrench until
hand tight. Seat the piston seal bottom ring into the
groove.
8. Using the hoist, raise the rod assembly back into a
vertical position taking care not to damage the OD seals
on the head and piston.
9. Apply anti-seize lubricant to the head outer threads.
10. Lubricate the OD seals on the piston and head with
clean light oil and lower the assembly into the barrel.
Stop just before the gland enters the barrel. Using the
spanner wrench turn the head counterclockwise while
applying light downward force until the threads engage.
11. Continue turning the head counterclockwise until the
thread clicks, then reverse direction to clockwise and
thread in until there is no gap between the head
shoulder and the top of the barrel.
12. Install the setscrew with a 5/32 inch allen wrench until
hand tight.
13. Slowly lower the rod to the fully retracted position.
NOTE: Oil or oil/air mixture may rapidly exit out of the ports
during retract. Shield the work area from the exiting
oil.
14. Install the plugs.
Test
1. Set test stand pressure to 310.1 bar (4500 psi).
2. Attach hose fittings to cylinder.
3. Connect a ball valve to the “test extend” port (marked
“PC” on rod mount) so that the pressure can be released
after testing and is not trapped in the valve. Test cylinder
through working ports with ball valve closed.
4. The cylinder shall be stroked its full length in both
directions to fill it with oil and remove trapped oil.
5. Pressurize to recommended test pressure at each end,
beginning with the rod end for a minimum of 10 seconds
per end. While under pressure, cylinder shall be
checked for leaks at welds, SAE fittings, valve, and all
external static and dynamic seals. Refer to
Outrigger
Circuit , page 8-26 for outrigger jack cylinder Internal
Leak Testing. Cycle cylinder completely (retract and
extend) three times under pressure.
6. When testing is complete, relieve pressure on working
ports. Slowly open ball valve on PC port to relieve
trapped oil pressure. Plug the extend port (marked
“EXT”) and retract the cylinder with air using a regulator
at the RET port and a return line connected to the PC
port. Reclaim all oil. Carefully bleed off air pressure once
cylinder is fully retracted.
7. Seal ports with port plugs to prevent contamination from
entering cylinder.
CAUTION
When installing new seals and rings, avoid stretching
seals or scratching the grooved or gland surfaces. Make
sure parts are clean before and during assembly. Make
sure seals and rings are installed in the proper order.