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E5.3
HYDRAULIC CONTROL DEVICE
Hydraulic control devices shall be incorporated into the hydraulic circuit with
details as follows:
(a) Shut-Off Valve
Installed in the circuit which connects the cylinder(s) to the non-return valve
and the down direction valve(s).
(b) Non-Return Valve
Installed in the circuit between the pump(s) and the shut-off valve. Capable
of holding the vertical lifting platform installation with the rated load at any
point when the supply pressure drops below the minimum operating
pressure. The closing of the non-return valve shall be effected by the
hydraulic pressure from the jack and by at least one guided compression
spring and/or by gravity.
(c) Pressure Relief Valve
Connect to the circuit between the pump(s) and the non-return valve. The
hydraulic fluids shall be returned to the tank. To limit the pressure to 140%
of the full load pressure.
(d) Down Direction Valve
It shall be held open electrically. Closing of which shall be effected by the
hydraulic pressure from the jack and by at least one guided compression
spring per valve.
(e) Rupture Valve
Where required, rupture valve shall be capable of stopping the vertical
lifting platform installation in the downward movement, and maintaining it
stationary, in the event of failure of any part of the hydraulic circuit.
(f) One-way Restrictor
Where required, one-way restrictor shall prevent the speed of the vertical
lifting platform with rated load in downward movement exceeding the rated
speed downwards by more than 0.15 m/s.
(g) Filters
In the circuit between the tank and the pump(s), and in the circuit between
the shut-off valve and the down direction valve(s) shall be accessible for
inspection and maintenance.
Section E5
Page 2 of 3
LF_GS
2012 Edition