TP-9647
Revised 11-18
TP-9647
(16579)
Revised 11-18
Printed in the USA
Copyright Meritor, Inc., 2018
Page 1
Technical Bulletin
Inter-Axle Differential (IAD)
All Meritor
Tandem Drive Axles
Introduction
The Meritor Inter-Axle Differential (IAD) is a driver-controlled, air-
actuated traction device that allows for speed differences between
the forward and rear tandem axles while providing equal pulling
power from each axle of the tandem. By activating the IAD switch
located in the vehicle dash, improved traction is provided for each
axle.
The Inter-Axle Differential (IAD) is also known as a “Power Divider”
or “Third” differential.
Operation Tips
1.
The IAD is driver controlled.
2.
The IAD switch should be in the “UNLOCK” position for normal
operating conditions where there is good traction.
3.
Lock the IAD when approaching or anticipating icy or poor
driving conditions to provide improved traction. Relieve torque
prior to engaging the switch by letting up on the accelerator
pedal.
4.
Always unlock the IAD when the need for improved traction has
passed or when the vehicle is on a good road or highway.
5.
After locking or unlocking the IAD, let up on the accelerator to
provide an interruption in torque to the drivetrain. Activating the
IAD lock is similar to shifting a manual transmission with a
clutch.
6.
Do not actuate the IAD switch while one or more wheels are
actually slipping, spinning or losing traction, or damage to the
axle can result.
7.
Do not spin the wheels with the IAD unlocked, or damage to
the axle could result.
