Theory Of Operation - Genie S-100 Service Manual

First Edition • First Printing
Power Source
The Genie S-100, S-105, S-120 and S-125 are
powered by one of three diesel engines:
the Cummins B3.9L, the Deutz F4L 913 and the
Perkins 1004-42.
Auxiliary power is supplied by a hydraulic pump
powered by a 12V battery.
Hydraulic System
All machine functions are performed by the
hydraulic system. The hydraulic system can be
divided into two groups: Boom and Steer/Axle
functions and Drive functions.
Boom and Steer/Axle functions are powered by
two-section gear pumps, rated at 17 gpm (64.4 L/
min) and 10 gpm (37.9 L/min). When the engine is
running, these pumps supply hydraulic fluid under
pressure to function manifolds, where the
directional and flow control valves are located. To
protect from over-pressurization of the systems,
each manifold is provided with a pressure relief
valve. The Steer and Axle extend/retract manifold
relief valve is set at 3000 psi (206.8 bar); the
Function manifold relief valve is set at 2600 psi
(179.3 bar); the Platform manifold relief valve is
located in the Distribution manifold and is set at
3000 psi (206.8 bar).
Drive functions are powered by a bi-directional,
variable displacement piston pump rated at 28 gpm
(106 L/min) @ 2350 rpm. Two internal 4250 psi
(293 bar) relief valves are used to prevent over-
pressurization of the closed loop drive system.
Part No. 62401

Theory of Operation

The boom lift cylinder, boom extend cylinders,
platform leveling slave cylinder, platform rotator
and jib boom cylinder (S-105 and S-125 models)
incorporate counterbalance valves to prevent
movement in the event of a hydraulic line failure.
A regeneration circuit is used to increase the
performance of the primary boom extension
function. This circuit transfers hydraulic fluid from
one end of the primary cylinder into the other end
when the cylinder is extending or retracting.
The auxiliary pump is a two-section gear pump.
One section is rated at 1.85 gpm (7 L/min) and the
other is rated at 0.59 gpm (2.2 L/min).
The 1.7 gpm (7 L/min) section is supplied with a
2500 psi (172.4 bar) relief valve and the 0.59 gpm
(2.2 L/min) section is supplied with a 3000 psi
(206.8 bar) relief valve.
Electrical System
Two separate 12V batteries are used for this
system. The larger, Group 4D, battery is used to
start the engine and power the auxiliary pump. The
smaller, Group 31, battery is used to power the
three Electronic Control Modules (ECM's) which
manage boom functions and engine controls. The
batteries are charged through a common engine
driven alternator. A battery separator is used to
charge the smaller battery before charging the
larger battery. The control system is protected by
two circuit breakers that may be manually reset.
Genie S-100 & S-105 & S-120 & S-125
Section 3 • Theory of Operation
3 - 1