TP-9648
TECHNICAL BULLETIN
Revised 11-18
TP-9648
(16579)
Revised 11-18
Printed in the USA
Copyright Meritor, Inc., 2018
Page 1
Technical Bulletin
Inter-Axle Differential (IAD), and
Driver Controlled Main Differential
Lock (DCDL)
All Meritor Tandem Drive Axles
Equipped with Both the
Inter-Axle Differential (IAD), and
Driver Controlled Differential Lock (DCDL)
Introduction
All Meritor tandem axles are equipped with Inter-Axle Differential or
IAD. Drivers may lock the IAD to improve traction when encountering
adverse winter road conditions. The IAD lock may be used at all
speeds and for long time periods depending on bad weather
conditions such as rain or snow.
Optional DCDL is available in either the forward axle only, the rear
axle only or in both axles of the tandem. This option is available on
most models of Meritor tandem axles. The DCDL is used during
on- and off-highway operations that encounter slippery road
conditions and/or uneven terrain. It is used only at low speeds while
traveling through an area with poor traction conditions and is
deactivated as soon as the vehicle is through
the area.
Drivers may lock BOTH the IAD and the DCDL for maximum traction
under icy, snowy or poor road conditions. However, when using both
of these traction-enhancement devices or the DCDL alone, vehicle
speed must remain at 25 mph or less.
Recommended Procedures for using Both the IAD
Lock and DCDL Lock
When encountering poor road or highway conditions where
maximum traction is required, perform the following:
1.
When approaching poor traction conditions, first engage the
IAD switch. As conditions worsen and when vehicle travel
speed is 25 mph or less, the DCDL lock can then be engaged.
2.
When the DCDL is locked, the vehicle’s turning radius will
increase. This condition is called “understeer.” The driver must
use caution, good judgment and drive at low speeds when
operating the vehicle with the DCDL locked.
3.
There are no speed or handling restrictions for vehicle
operation with the IAD lock engaged. But for best axle
performance and minimum tire wear, ALWAYS unlock the IAD
lock when favorable road conditions return.
4.
When the DCDL is locked, the vehicle must be operated at 25
mph or less. Lock the DCDL only when maximum traction is
needed.
5.
Do not lock the DCDL when the vehicle is traveling down steep
grades, or potential loss of vehicle stability could result in a
jackknife of tractor and trailer.
