TM 5-3810-300-24&P2
To accommodate these changes, the I.D. of the adjusting plunger has also been counterbored to make room for the
snap ring.
If the original adjusting sleeve (actuator) which does not have the new counterbore (has internal threads the full length) is
to be used, do not employ the adjusting bolt retainer (snap) ring. Use of the retainer (snap) ring with the old style
adjusting sleeve (actuator) and new style adjusting bolt would prevent the adjusting bolt from moving outward and
making the necessary lining wear adjustment.
In addition, the adjusting bolt now has a machined smooth wiping surface under the head to accept a new single lip
plunger seal.
This seal is designed to allow more flexibility and will provide additional protection for the adjusting assembly when the
bolt is extended outward in brake application. Thus, this will reduce the possibility of the adjusting bolt freezing, due to
any corrosion or dirt inside the actuation housing.
The adjusting assembly also employs a new single lip plunger seal to provide more protection for the bolt threads and
improved sealing for the actuation housing components. The lip of this seal wipes against the smooth machined surface
beneath the head of the bolt.
To protect the plunger seal, the head of the adjusting bolt incorporates a redesigned stamped seal protector and rolled
spring lips. The seal protector is angled downward to act as a shield over the plunger seal. This prevents contact
between the seal and the adjusting spoon when the brake is being adjusted manually. The spring lip serves to protect the
plunger seal when the bolt is in the bottomed position.
To further facilitate the initial manual adjustment, the star wheel portion of the adjusting bolt head employs square teeth.
The adjusting pawl for the Stopmaster II Wedge brake employs an integral key which mates with a slot in the adjusting
pawl guide hole of the redesigned brake spider of actuation housing.
The power unit of the Stopmaster II employs a larger, and more flexible diaphragm boot seal. It also employs a boot
retainer clamp which is riveted to the wall of the non-pressure half of the housing. The lip of the diaphragm boot is
positioned beneath the boot retainer clamp, and is thus held tightly against the wall of the non-pressure housing. This
provides improved sealing for the air chamber tube by preventing road contaminates from entering the wedge area and
contaminating the lubricant. Further, the mechanical attachment of the boot retainer clamp prevents possible separation
of the diaphragm boot from the housing.
Other design improvements for the Stopmaster II include a chamfer on the brake drum on the inside outer edge to
facilitate removal when brake service is necessary. The chamfer allows the brake lining to overlap the drum edge by
approximately 1/16". This, in turn, prevents the development of scored wear rings on I.D. of the drum, which could
interfere with disassembly.
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