Hydraulic Power Lift Operation; Hydraulic Lift Pump Components - Fiat 411 R Service Manual

We give hereafter the specifications oi the hydraulic pump, to check its performance:
._ ratio between engine and pump R.P.M. . . . . . . . . . . . . . . . . . -L152
_ pump speed (with engine at rated speed, 2390 R.P.M.) . . . . . . . . . 2.000 R.P.m_
H gump rotation, as viewed from driving shaft end . . . . . . . . . . . . (clout-(W339
_ suction heed . . . . . . . . . . . ~ . . . . . . . . . , . . . . . . $380 mm (,+_'l2.8Hi}"}
__ deliveries {oil at temperature at G kg/'sq.cm (O p.s.i.) . . . . . . . . . 1? litersfmin (3.75 lmp,gal'_]
or 5005 -1409?) at 150 l<g;'sq.cm (21335 p.s.i.) . . . . . . 16.5 litersfmin (3.fi5lfl1p,gal_)
- pressure valve opening pressure (marked C or E) . . . . . . . 145-'SS5 kg/sq.cm (2862-2205 p.s.l.)
To secure a good performance of the lift hydraulic pump, use exclusiveh/SAE 20 hydraulic oil avoiding
all mixtures. l .
The customer shall be warned that periodical checks and cleaning of the hydraulic lift oil filter is absolutely
necessary. After the first 20 hours from any oil change clean accurately to remove dirt from the litter.
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Fig. 173. - Hydraulic lift pump components.
1. Shahi bushes - 2. Forward cover - 3. Delivery port.
HYDRAUHC POWER LIFT OPERATION
The power litt consents performing two different operations: position control and draft control. To
choose either one just move lever B (Fig. 172) downwards in the former case and upwards in the latter.
The lever can be actuated only when the litt arms are raised.
The lift arm raising or lowering control is performed by lever A. in the position control operation, at
every position of lever A corresponds a dltterent height of the lift arms, and consequently of the imple-
ment. in the draft control operation most of the excursion in the quadrant is used to determine the draft at
the implement during work.
Whenever lever A is moved, the control valve spool rotates and according to its sense of rotation lets
oil pass in ditiereni conditions through the valves of the hydraulic circuit which control the raising or the
lowering of the arms. in the position control operation, the height of the arms can be controlled through
lever A only, white in draft control also intervenes the reacting force which the implement passes on to
the spring M, Fig. 175. The deformation of the latter consents the rotation of the control valve spool,
(the strain of the spring being transformed by a lever mechanism) and consequently a movement oi the
arms which brings the resistance encountered by the implement in the ground back within the limits
established by the position of the lever A in its sector.
In position control operation the selector lever B, acting on the relative position oi levers and rockers
of the linkage cuts oh' the control valve spool from the effects oi the strain set by the implement on
spring M.
Fig. TF6 illustrates the hydraulic diagram of the system. For further details on the power lift operation
see the Technical information Bulletin, Form No. 324.192.
120
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