TM 5-3810-300-24&P2
The Super "B" Fail-Safe II is an emergency and parking brake power unit designed to be used with Stopmaster wedge
brakes. This Fail-Safe unit also incorporates a series of changes (based on the original Super Fail-Safe unit) that will
provide improved service life and simplified maintenance. These improvements have been made to six components:
The nut pre-load spring; a redesigned foot; the cap and piston radii; the retainer spring lock; the double seal construction,
and; a vinyl coating on the power spring.
The caging bolt employs a double seal construction beneath the head of the bolt for improved sealing. This keeps road
contaminants from entering the Fail-Safe unit and corroding the inside of the chamber. Further, this double bolt seal
design also provides more support and better alignment for the caging bolt assembly.
The caging bolt and nut assembly employs a nut preload spring to replace the original hex nut. This preload spring
applies continuous pressure against the caging (square) nut, holding the nut adjacent to the last thread of the bolt. The
assurance of thread engagement, provided by this caging bolt design facilitates caging the Fail-Safe unit when brake
service is necessary.
The piston foot incorporates a machined bore to accommodate the caging bolt and nut preload spring assembly. It also
employs an "O" ring for added sealing. Further, the foot and seal assembly is threaded into the piston, and held securely
in place with the use of Loctite sealant. This eliminates the need for a set screw.
Electric System. (Illus. 4-20 and 4-21).
Electric power for the Superstructure and Carrier components is supplied by a 60 AMP engine driven alternator. Electric
power for operation of lighting and certain accessory components is provided by one of the 12 volt batteries. Power for
engine starting is provided by four 12 volt batteries connected in series/parallel. The Electric System has a alternator
safety switch. The switch prevents the alternator from coming on the line until the oil pressure reaches a predetermined
pressure.
Heaters.
The carrier cab is supplied with a hot water circulation type heater.
Hot water for the circulation heater is taken from the engine Coolant System. The water is carried by hoses to cores.
When heat is desired in the cab, the shut off valve is opened. With the shut off valve opened hot water flows to the
cores. A switch located in the cab controls operation of the fan that blows the hot air exhausted from the core into the
cab.
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