SERVICE MANUAL
CONSTRUCTION
The basic functions having been designated, let’s
look at conventional universal joint and driveshaft
construction.
To transmit required loads, the driveshaft must
possess high strength. Forged steel, or high strength
cast yokes are generally used to provide necessary
strength and the rigidity required to maintain bearing
alignment under torque loads and during high speed
operation. Special high-strength tubing is used to
provide maximum torque carrying capacity at minimum
practical weight. This tubing must be securely welded to
its end members, to provide the necessary torque
capacity.
High quality anti-friction bearings are used to
withstand required loads while oscillating at high speeds.
These bearings on the journal cross carry very high
loads for their size. The full complement, roller-type
(needle) bearings are generally used because of their
high capacity in a limited space. Bearings are
individually sealed to provide retention of required
lubricants as well as to prevent the entry of foreign
material. If lubricants become contaminated with water
or abrasive material, needle bearing life is seriously
affected.
Abrasive material is a major problem where a vehicle
operates under conditions of extreme moisture and dirt.
Off-highway installations are especially critical in this
respect. Military trucks represent the extreme in this
direction and were the first to show the shortcomings in
the conventional cork seals used in universal joint
bearings. It was found that an improved seal was
required for this type of operation. Synthetic rubber-type
seals were developed for these installations. These
seals have been in use for many years on military
vehicles and are now used in most commercial
installations. The improved sealing shows increased life
and a less critical re-lubrication cycle.
The sliding splines between slip joint and permanent
joint must support the driveshaft and be capable of
sliding under full torque loads. To provide adequate
strength and wear resistance, hardened and ground
splines are used. These splines are phosphate or nylon
coated to resist galling and to reduce sliding friction.
CTS-4017 - Page 5
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