MS Transit Solutions




ETCOM S-Cam Bushing Webpage
“Long Life No Grease Bushings”

Linings contaminated with grease form a glaze which decrease braking forces.

Glazed drums can overheat and crack weakening the part and compromising safety.

Glazing also greatly shortens the life if the lining and the expensive drums.

Once glazing has occurred the braking forces are different on each side of the vehicle.

No Grease bushings are a significant safety improvement

* ETCOM S-Cam Webpage”Long Life No Grease Bushings” ™ never require grease

* Will not melt at high temperatures

* They will not “squash-out” at high shock loads as nylon does

* Greatly prolongs the life of brake linings, drums, and “S” Cam shafts

* Maintains the tight tolerance of the brake system. This is a big advantage for the slack adjusters and anti- lock brake systems.

* Eliminates brake squeal caused by worn bushings and shafts

* Not affected by road grime or any oils or fuels

* Easy to install...Press fit (As per the current method)

* Greatly reduces your maintenance manpower needs by reducing your vehicle down time and increasing your revenue generating operating time with 3 - times your present bushings life.

MS Transit Solutions LLc (MSTS) are the Sales Representatives and Exclusive Distributors for the Bus Transit market in the USA and the Rail Transit and Freight Rail markets in North America for these and other ETCOM Inc. products.

©MS Transit Solutions LLc

Thermoset Composites vs Thermoplastics

Some Essential Differences

ETCOM Products WebsiteThere is an essential difference in heat resistance between thermoplastics and thermosets.  In thermoplastics, the absence of any appreciable cross-linking makes them subject to catastrophic failure almost immediately after the heat distortion point is reached.  In a cross-linked THERMOSET, thermal degradation is slow (relatively) at temperatures well above the heat distortion point.  Thermal extrusions have little or no effect on THERMOSETS.
When discussing thermosets more specifically, the maximum temperature to which moldings may be subjected without major physical change is determined by four factors:
    Temperature environment at which the binder decomposes.
    Temperature environment at which the filler decomposes.
    Thermal history of the molded parts.
    Length of exposure time at maximum temperature. 
    U.L. tested the various electrical properties for 50,000 to 100,000 hours in or out of ovens.

Note that temperature limits, when exposure time is in the order of seconds or milliseconds, materials which normally would not be suitable for continuous service above375°F, have withstood extremely high temperatures, perhaps up to 5000°F.  We can produce electric tubes that quench the arc flash of lightening 3 successive times without failing.
THERMOSETS will not melt under blow torch temperatures, but they will turn red hot and combine with oxygen and char which is called “Ablation”.

ETCOM Color Parts WebsiteThe "curing" of thermosetting resins entails making larger and more cross-linked molecules out of smaller molecules.  Curing is a process which is always accompanied by a shrinkage of the resin involved, the amount of shrinkage being dependent on the molecular changes involved and the completeness of cure.  In addition, with some resin types, volatile by-products are produced during cure.  For example, the isocyanates liberate carbon-dioxide; while melamine, urea, and phenolic resins liberate water during the cure process.  If the volatiles are not entirely eliminated slowly during the cure, the moldings may blister if suddenly subjected to thermal shock.  Usually these volatile substances can be slowly expelled by slow heating, which also results in greater degree of cure.

ETCOM Part WebsiteIt is a general rule that to assure resistance to thermal shock at any given temperature (up to the decomposition temperature), the plastic part should previously have been exposed to that temperature.  This may be accomplished by post-cure in circulating air oven in which the part will be exposed in service.  The maximum permissible rate of oven-temperature rise in the post-cure schedule will depend on the rapidity with which volatiles are diffused from the molding.  The rate of volatile escape is greatest along reinforcing fibers. In the absence of fiber orientation, the volatile substances will escape via the shortest path through the molding.

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