Lull 6K Service Manual - Manual (Page 551)

Transmission
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 8-3
The 3- or 4-speed WG100 transmission consists of a torque converter
coupled to a multi-spool powershift transmission with an integrated
transfer case. The 3-speed design has three forward and three reverse
speeds. The 4-speed design has four forward and three reverse
speeds. Speed ranges and direction can be engaged and disengaged
under load with hydraulically-actuated multidisc clutches.
3. Transmission Harness Connection DW-3 Shifter to Transmission
Solenoid Valve Assembly
a. 65011D — Harness
b. 65899A — Connector Assembly (not used with 4-speed
transmission)
c. 37657X — Declutch Relay
d. P21787 — Diodes
The transmission harness adapts the vehicle’s power supply to the ZF
transmission and completes the electrical connections between the
DW-3 speed range/direction selector, the solenoids at the transmission
valve assembly, the declutch relay, and the shunt diodes.
The function of the declutch relay is to inhibit power into the shifter
from the vehicle’s electrical supply into the shifter when the boom is
above 40°, when the park brake is applied, or when the service brake
is applied and the transmission disconnect switch is in the “ON”
position. This results in no directional signals exiting the shifter to the
transmission’s M1 or M3 directional solenoids. If the declutch relay is
functioning correctly, the transmission should not engage when the
boom is above 40°, when the park brake is applied, or when the
service brake is applied with the transmission disconnect switch in the
“ON” position.
The five shunt diodes function to protect the contacts of the rotary and
micro switches in the DW-3 shifter. When the rotary and micro switches
inside the DW-3 shifter are closed and then opened, magnetic fields
around the activated transmission valve solenoids collapse, creating
reverse polarity or negative voltage. Reverse polarity spikes or
negative voltage spikes can seek a path of lesser resistance to ground
through the shunt diodes rather than arcing and damaging the switch
contacts of the DW-3 shifter (see page 8-16 for more information).
4. Vehicle Electrical System
The ZF transmission will not operate without an uninterrupted 12 volt
power supply. The recommended operating voltage is 10.5–16.5 volts.