Etesia HYDRO 124D Technical Training Manual page 35

4.2) The equipment circuit.
WARNING : HYDRAULIC FLUID UNDER PRESSURE CAN HAVE ENOUGH
FORCE TO PENETRATE THE SKIN. IN THE EVENT OF AN ACCIDENT
CONTACT A DOCTOR OR THE NEAREST EMERGENCY SERVICES
IMMEDIATELY.
Always use measuring equipment that is in good condition. Always ensure that the
instrument is appropriate for the measurement to be made.
The tandem pump generates two distinct flows. These flows depend directly on the speed of
the diesel engine.
The engine speed varies between 1200 rpm (idling) and 2850 rpm (max. rate) inclusive. The
camshaft (at the end of which the tandem pump is mounted) turns at half the rate (see engine
chapter). The rotational speed of the tandem pump is therefore situated between 600 rpm
(idling) and 1425 rpm (max. rate). Using one of the formulae given in chapter 4.1, we find the
following flows :
Equipment circuit (4cc) :
Power take-off CIRCUIT (16cc) :
The function requiring the most effort (power) is the lifting of the grassbox when the latter is
full. It is therefore this function that imposes the maximum necessary power that the 4cc
pump must provide.
A grassbox full of grass weighs approximately 200kg. For each ram, that represents 720kg
(because of the lever arm). The characteristics of the ram are 32/20/311. The active surface
of the piston (the surface on which the oil will press) is that of the large chamber side. To lift
the grassbox, a force of 720kg must be exerted on the active surface of the piston.
Pressure necessary to lift a 200kg grassbox : 90 bars
For safety's sake, we have added 20% to this value in determining the adequate pressure
limit.
Maximum pressure of the equipment circuit : 110 bars
The pressure limiting device for this circuit is placed in the ORBITROL. Its calibration is
fixed : it is not adjustable.
This pressure may be checked at the front of the machine, on the small quick acting
couplings on the coupling plate.
Method : Connect a manometer that allows the reading of pressures up to 120 bars minimum
onto one of the small male hydraulic couplings. Activate the accessory ram control switch
situated on the steering console. The diesel engine must be running at max. speed whilst
the measurement is taken.
2.4 < Q < 5.7 l/min
4cc
9.6 < Q < 22.8 l/min
16cc
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