Function of Manual Slack Adjusters (MSA)
MSA is a sub assembly in the air brake systems of medium and heavy commercial vehicles.
The Slack Adjuster transmits the force from the brake chamber to the camshaft in the foundation brake of an Air Brake System on HCVs, buses and trailers.
MSA also provides for adjustment of the brake shoe clearance, whenever it increases due to brake lining wear. This adjustment is carried out manually by rotating the worm shaft, which, in turn, rotates the worm wheel and repositions the "S" Cam, to maintain the required shoe clearance.
The worm shaft is kept located in that position to prevent it from rotating due to vibration or during normal braking operation.
A legislation was enacted in Europe and North America in 1996, mandating that trucks, tractor-trailer combinations and passenger buses with air brake systems should be fitted with Automatic Slack Adjusters (ASA) instead of Manual Slack Adjusters, as an original equipment..
Function of Automatic Slack Adjuster(ASA)
The Automatic Slack Adjuster is an advanced version of the Manual Slack adjuster. In an automatic slack adjuster, a sensing device in the slack Adjuster body automatically adjusts the normal operating clearance between the brake shoe and the brake drum created by wear in the brake lining. The product is a highly technically oriented one.
Slack Adjuster:
Operation:
The Adjuster is a clearance sensing brake adjuster that senses the lining to drum clearance and adjusts, if necessary, on the release of the brake.
The Haldex ABA helps ensure maximum brake performance with minimal maintenance. Backed by the longest warranty in the industry, they actually pay for themselves through increased service life.
Features and Benefits:
Clearance sensing design and built-in mechanical intelligence avoid over adjustment that causes uneven braking and premature lining wear
Lower maintenance cost and greater vehicle utilization
Greater adjuster reliability
Unique control arm design simplifies installation
No installation templates required
Eliminates the high cost and maintenance of linkage style adjusters
No special air chamber clevis required
Allows for efficient O Ring sealing of the adjuster for long life
Integrated installation indicator confirms correct installation
Reduces maintenance costs
First no-lube and extended lube ABA which decreases vehicle down time
Totally seals unit to extend maintenance intervals
Heat-treated housing and chromic-moly gears
Increased life and durability
Designed to operate in the most difficult applications
Longest warranty in the industry
Adjuster configuration available to fit on all applications
Wide range of adjusters to fit on unusual applications from large offsets to 12-1/4" brakes
O ring seal prevents contamination
Cone clutch components are cold forged for durability.
Built-in installation indicator confirms correct installation.
Unique control arm eliminates linkage wear problems and provides greater application flexibility.
Heat treating the adjuster housing, a step only Haldex takes
Reduces internal wear and provides longer service life
Wormshaft benefits from an exclusive after rolling process that extends fatigue life.
O Ring seals eliminate troublesome rubber boots.
Worm wheel uses chrom-moly gears and a buttress tooth gear configuration to reduce gear stress and prolong service life.
Air Brake Chamber:
Operation:
Application ?application from the control valve is admitted into the inlet port on the pressure housing behind the diaphragm. When the pressure overcomes the force of the relatively lightly loaded return spring, the diaphragm flexes forward, moving the internal plate and push rod, applying a force to the brake mechanism.
Release - when the control valve is returned to the release position, the air pressure is removed from the brake chamber, allowing the brake mechanism to return to the initial release position.
Features and Benefits:
Special electro deposited epoxy coating
Providing superior corrosion resistance for cover assembly and pressure housing
Heavy-duty natural rubber diaphragm
Nylon reinforced for maximum service reliability
Fatigue resistant diaphragm push plate
With riveting providing a safe, secure, permanent attachment system
Orange stroke indicator
Shows the operator at a glance if the brake is in adjustment or if it needs servicing
Top and side air inlet ports
For convenience of hookup
Low profile design
Dampens vibration and reduces shear-load force
Large head mounting studs
Of Grade 5 steel that are press fit into the non-pressure housing giving a reinforced mounting surface which reduces fatigue
Designed for s-cam and disc brake applications
Available in sizes from 9 square inches (type 9) to 36 square inches (type 36)
Spring Brake Chamber:
Operation:
The operating principal is sound and simple. There are two sections to a DDSB (double diaphragm spring brake) assembly.
The front section is the service brake section that operates like any other service brake chamber, in that it converts modulated air pressure from the brake valve into a mechanical force to apply the foundation brakes.
The rear section is the emergency/parking section and contains a very strong coil spring that applies the brake mechanically when air pressure is exhausted / loss.
The coil spring is held compressed by air pressure from the main air system. If the air pressure is removed for any reason (driver applying park brakes or catastrophic failure in the air system), the force of the coil spring is transmitted through an internal pushrod to the service brake pushrod, applying the brake.
Features and Benefits:
Tamper-Resistant Spring Housing
Eliminating the potential of serious injury
Special Electro Deposited Epoxy Coating
Providing superior corrosion resistance for non-pressure housing, power spring housing, and power spring
Externally Stored Release Bolt w/Hardened Steel Washer
Which reduces service time and caging effort
Fatigue Resistant Diaphragm Push Plate
With riveting providing a safe, secure, permanent attachment system
Orange Stroke Indicator
Shows the operator at a glance if the brake is in adjustment or if it needs servicing
Captive Dust Plug
Reducing the long-term chances of contamination
Delrin Center Guide Bearing
Reduces friction and gives longer life expectancy
Low Profile Super Duty Non-Pressure Housing
Epoxy coated nine-gauge steel provides superior impact and corrosion resistance
Large Head Mounting Studs
Of Grade 5 steel that are press fit into the non-pressure housing giving a reinforced mounting surface which reduces fatigue
