"2047ES / 2647ES / 3247ES" Service & Parts Manual - CE Specifications
March 2008
Page 1-9
PLATFORM LIFT CIRCUIT
Note:
Refer to
Hydraulic Manifold and Relief Pressure Adjustment Procedure.
Refer to
Section 3 for Remove and Replace instructions.
• The lift system uses the hydraulic pump to obtain proportional lifting function controlled by
the lift valve and pump speed.
• Lowering is single speed controlled by the holding valves on the lift cylinder(s) and regu-
lated by a fixed orifice located on the lift cylinder(s).
• Platform capacity is limited by a hydraulic relief valve in the lift circuit. (Refer to Machine
Specifications or the Hydraulic Schematic for proper setting).
Lift Cylinder
Note:
Refer to
Cylinder Repair.
2047ES / 2647ES
One (1) single acting type hydraulic cylinder.
The cylinder has an integrated 2-position, 2-way solenoid operated platform lower valve for hold-
ing the platform in position.
The valve is also externally actuated for manually lowering the platform. Early models use a pull-
to-release knob at the cylinder, while current models use a cable release with a pull handle lo-
cated near the ladder (see
Emergency Systems and Procedures).
3247ES
Two (2) single acting type hydraulic cylinders.
Each cylinder has an integrated 2-position, 2-way solenoid operated platform lower valve for
holding the platform in position (see
Emergency Systems and Procedures).
The valves are also externally actuated via a toggle switch for manually lowering the platform.
The normally closed holding valve prevents retraction of the cylinder rod should a hydraulic line
rupture or a leak develop between the cylinder and its related control valve.
