Some aviation support equipments, such as tow
tractors, have rear axle planetary gears at the wheel end
of the axle. These gears further reduce the power
LEARNING OBJECTIVES: Identify the
purpose of exhaust systems. Identify the
between the axle and the wheel. The axle has a gear on
components of an exhaust system. Identify
the outer end, which turns three planetary pinion gears;
procedures for removing and repairing exhaust
these turn an internal ring gear bolted to the wheel.
This system is all lubricated by the same gear oil that
lubricates the differential. For adjustment and
The purpose of the exhaust system is to channel
servicing, consult the manufacturer's instructions.
harmful exhaust gasses to the rear of the vehicle.
This system was developed to prevent the driver and
passenger(s) from inhaling the harmful gasses and
becoming ill. The exhaust system attaches from the
While transmissions, propeller shaft assemblies,
exhaust side of the engine head, but it must be
differentials, or rear axle assemblies are not usually
supported elsewhere as the system is made of light
dangerous to work on or service, all safety precautions
weight pipe and will not support itself. The most
related to mechanical work must be followed to
logical place to put the exhaust system is under the
frame assembly where it can hang by hangers, called
prevent injury. These assemblies are heavy when
muffler hangers. They not only support the weight of
removed as units, and the simple act of dropping one of
the system but also help absorb the vibrations that
them can cause a serious injury.
could cause metal fatigue. Although the exhaust
In addition to the usual safety precautions, it
system is under the frame it normally does not hang
below the lowest part of the chassis. This helps
should be reemphasized that proper blocking of the
prevent it from being ripped off by flight deck
vehicle being worked on is always a safe practice.
arresting cables or road hazards on shore bases.
In addition, when one end of a vehicle is raised
Most exhaust systems are made up several pieces
from the ground, a minimum of two safety stands
of pipe and a muffler, as shown in figure 2-91. Some
should be used in place of the jack or lifting device that
original equipment may be one-piece systems, but
was used to raise the vehicle. It is never a safe practice
replacement parts are made up of several pieces.
to be under a vehicle when it is held off the ground only
To remove and replace the exhaust system, you
by lifting devices.
should remove the section to be replaced by unbolting
the attaching hardware and removing the items to be
Q2-36. What types of drive axles are most commonly
replaced with proper replacement items. Tighten the
used in SE?
system hardware to the manufacturer's specifications.
Direct drive axles
Independent drive axles
N OT E : A lwa y s r e f e r t o t h e M a i n t e n a n c e
Ridged drive axles
Instruction Manual (MIM) when performing any
Full-floating drive axles
maintenance on support equipment.
Figure 2-91.--Typical exhaust system.