Kalmar Ottawa t2, Maintenance Manual

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104 9.10 Construction and Suspension of Cab/Deck – 9 Frame, Body, Cab and Accessories
Maintenance Manual Ottawa T2 4x2
page –
Cab Tilt (Hydraulic) Components
Cab Tilt Cylinder and Safety Prop
The cab tilt system is an electro/hydraulic system that utilizes
the tractor battery to power an electric motor that drives the hy-
draulic pump. The inlet port of the pump draws in hydraulic oil
from the common reservoir. This fixed displacement pump forc-
es the oil through its outlet port, through the valve pressure
passage, out the work port, and to the base end of the tilt cylin-
der. Because of the load, pressure rises until the piston moves
the rod, thereby raising the cab. If the switch is held in the Up
position after the cylinder has fully extended, pressure will rise
to the relief setting of 3200 psi (221 bar). The relief valve will
open and pressure will not increase above the set point.
Electric Pump Motor — Cab Tilt
When tilting the cab back down, the solenoid-operated direc-
tional control valve (with two positions) is energized. The valve
shifts position and allows a return path for oil from the tilt cylin-
der. A one-way check valve blocks oil returning from the relief
valve and pump inlet and directs it through the valve passage.
It goes through a restriction, which is pressure compensated,
and then back to the pump inlet and on to the reservoir.
When the solenoid-operated control valve is de-energized, a
simple spring load returns it to the blocked position. The func-
tion of the return restriction is to slow the rate of oil exhausting
from the tilt cylinder. The effect of this restriction is to provide a
slow, controlled return to the Down position for the cab.
Cab Latch — One hydraulic cylinder and one mechanical lock-
ing mechanism are utilized to safely secure the cab in the
Down position. The locking fingers are spring-loaded to the
Lock position and are unlatched by the cylinder during the tilt
up operation. The latching cylinder simply tees into the work
line that connects to the base end of the tilt cylinder.
The latch cylinder and the tilt cylinder receive hydraulic oil un-
der pressure at the same time. Since the latch cylinders require
less pressure to operate, they will unlatch prior to the lifting of
the cab. After they are unlatched and pressure rises, the tilt cyl-
inder will extend, raising the cab.