Attachments
Section A Section A
7 - 5 7 - 5
9803/8500 Issue 1
Valve Block
General
The valve block consists of a number of segments A
sandwiched between end sections B and C, all held together
by three studs D and nuts E. The standard block has six
segments as shown in the plan view opposite. An optional
seventh segment, located adjacent to segment 6, is available
for the operation of a rockbreaker attachment. The main
relief valve (MRV) F is housed in the feed end section B.
Each segment is fitted with one of the following alternatives
at locations G, H, J, according to its function:
Segment G H J
1 - dipper X Y V
2 - bucket Z X V
3 - stabiliser (right) Z Z W
4 - stabiliser (left) Z Z W
5 - slew X X V
6 - boom Y X V
7 - rockbreaker Z ** W*
X - Standard ARV; Y - Anti-cavitation ARV; Z - Blanking plug.
*The operating lever for the rockbreaker service, the same
type as for the stabilisers, is not spring loaded. Springs K are
not fitted and the lever engages a detent to positively hold it
ON and OFF.
**In position H on the rockbreaker segment a pre-assembled
pressure release cartridge is installed. Do not confuse with
the blanking plugs used elsewhere which are similar in
appearance.
Dismantling and Assembly
Dismantling must be carried out in clean conditions, which
necessitates removal of the valve block from the backhoe.
The dismantling sequence is self-evident from the exploded
view. Take care not to drop any springs, poppet valves,
seals or other loosely inserted components when removing
relief valves or spool end covers, or when separating the
segments.
Note: Non-return valves L are held in place by means of one
of the studs D, which passes through holes in them. To
permit removal of L once the stud has been withdrawn,
insert a 5 mm threaded screw into the end of the valve.
Note: If either a spool or its housing is damaged, fit a new
segment/spool assembly.
Renew all seals.
If the segments have been separated, tighten the studs D/
nuts E to the torque below
Item Torque
D/E 343 Nm (253 lbf ft).
Backhoe
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