Holding Valve; Description; Maintenance - Manitowoc Grove RT770E Service Maintenance Manual

HYDRAULIC SYSTEM

HOLDING VALVE

Description

A bolt-on externally piloted manifold style holding valve is
installed on the lift cylinder and a cartridge style holding valve
is installed into each telescope cylinder port block.

Maintenance

Removal
1. Unscrew holding valve from its port block or manifold.
Installation
1. Check the inside of the port block or manifold for any
sharp edges or burrs and remove as necessary with
emery cloth.
2. Install new O-rings onto the holding valve.
3. Lubricate the holding valve and O-rings with clean
hydraulic oil.
2-46
Do not damage the O-rings during installation of the
holding valve. If the holding valve turns freely then gets
hard to turn, then easy to turn, remove the holding valve
and check the O-rings. They have probably been
damaged by a sharp edge of a port.
NOTE:
4.
5.
Published 11/26/2014, Control # 447-05
CAUTION
The holding valve should turn by hand until
compression of the O-rings begins.
Carefully install the holding valve into the port block or
manifold until fully seated.
Test the holding valve and port block or manifold by
operating the lift cylinder and/or the telescope cylinder,
as applicable. Verify lift cylinder and/or telescope
cylinder works without problems; verify there is no
leaking. Make repairs as needed.
RT770E