Repairing Hydraulic Parts; Dismantling The Head-Valve Units - Pratissoli HF Serie Manual De Reparación

Secure the PTO side flange to the casing, taking care with the
lip seal as described previously and tighten the fixing screws
to the recommended torque.
Then feed the flange on the indicator side without shims in
the carter and start to move it closer, manually screwing the
M6x40 service screws in equally, with small rotations such as
to move the cover in slowly and correctly.
At the same time, check that the shaft rotates freely by turning
it manually.
Continuing the procedure in this way, a sudden increase in
hardness during shaft rotation will soon be experienced.
At this point, halt the forward movement of the cover and
loosen the fixing screws completely.
With the aid of a feeler gauge, measure the clearance between
the side cover and pump casing (see Fig. 14).
Proceed to determine the shim pack, using the table below:
Detected Measurement
From: 0.05 to: 0.10
From: 0.11 to: 0.20
From: 0.21 to: 0.30
From: 0.31 to: 0.35
From: 0.36 to: 0.45
From: 0.46 to: 0.55
From: 0.56 to: 0.60
From: 0.61 to: 0.70
Fig. 14
Shim Type # pieces
/ /
0.1 1
0.1 2
0.25 1
0.35 1
0.35 1
0.10 1
0.25 2
0.35 1
0.25 1
Fig. 15
20
Once the type and number of shims have been determined
using the table, check the following: assemble the shim pack
on the indicator side cover centring (Fig. 15), secure the cover
to the casing, following the procedure in par. 2.1.2, and tighten
the screws to their recommended torque.
Check that the shaft rotation stall torque is between 4 Nm and
6 Nm.
If this torque is correct, connect the con-rods to the bend
shaft and to the next stages. If it is not, redefine the shim pack,
repeating the operations.
2.2

REPAIRING HYDRAULIC PARTS

2.2.1

Dismantling the head-valve units

Operations are limited to inspection or replacement of valves,
if necessary and, however, at the intervals indicated in the
"PREVENTIVE MAINTENANCE" table in chapter 11 of the Use
and maintenance manual.
The valve units are assembled vertically inside the head.
Operate as follows to extract them:
- unscrew the 8 M14x40 valve cover fixing screws (Fig. 16);
- using the extractor hammer code 26019400, extract:
A) Valve plugs (Fig. 17).
B) Outlet valve units (Fig. 18).
C) Valve bushes (Fig. 19), combined with tool
code 27513600.
D) Suction valve units (Fig. 20).
Fig. 16
Fig. 17