Brake Systems

sponsored by Haldex Commercial Vehicle Systems

Randy Petresh
Vice President Technical Services
Haldex Commercial Vehicle Systems
1-877-2HALDEX

Over 40 years of experience in the heavy duty industry. Randy holds a variety of degrees including: BSME, MSME and MBA. He is associated with the Society of Automotive Engineers SAE)...more»»

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Featured Question

LONG STROKE BRAKE CHAMBERS
Posted by Dave from Windsor, ON, CA on April 10, 2008

ARE THERE AFTERMARKET LONG STROKES WITH OUT IDENTIFYING TAG OR SQUARE PORTS…ARGUING WITH AN OWNER OPERATOR TELLING HIM TO CHANGE AND MATCH THEM UP?

Industry requirements for Long Stroke Chamber identification, i.e. square ports and special I.D. tags, were developed over 15 years ago. As a result, essentially all Long Stroke
Chambers manufactured in the U.S. over the past 10 years or so, will exhibit the long stroke identification requirements. However, older vehicles may still carry long stroke
chambers which pre-date the industry requirements. Imported units and some aftermarket only models may also not include the long stroke chamber identification
requirements.

Featured Question

Manual versus automatic
Posted by Mitch from Seattle, WA, US on February 12, 2008

Can I manually adjust an automatic brake adjuster?

NEVER mix automatic brake adjusters with manual brake adjusters or use different makes of automatic brake adjusters on the same axle and axel combinations (i.e. tandems).

trailer run in
Posted by Bob from Apex, NC, US on April 11, 2008

I’ve had 2 trucks & trailers with same problem. 1st truck 1984 peterbilt, with a 2001 city dump trailer, 2nd truck 1995 peterbilt & a 2005 transcraft flatbed. In both cases the truck felt like it was doing all the braking, replaced every brake valve from the foot pedal, check valves,tractor protection valve,I mean everything,still have same problem .trailers both abs, trucks none abs, but have center pin wired to work,same results if hooked to none abs trailer.it feels like trailer brakes are on time delay, if I pull down on trolley valve, it takes a few seconds before I can feel any trailer braking.local dealers want $ 300.00 to hook up abs monitor. Do you have any ideas or suggestions that I might be able to try?? also on my brake application gauge, it says that 40-60 psi of pressure is needed for a typical / average braking situations. thankyou for your time

Very difficult systems problem to explain and/or diagnose on paper. However, based on the brief description of the problem, and our past experiences, we believe that the trailer braking performance issues are due to contaminated trailer system braking control valves. This contamination and subsequent degraded performance is usually due to the presence of alcohol or glycol in the trailer braking system. As the contamination increases or persists in the system, the braking application pressures would also increase, as noted in the problem description.

Brake chambers
Posted by Nick from Buffalo, NY, US on February 10, 2008

When replacing brake chambers can I mix sizes?

If you replaced any brake chambers, insure you did not mix sizes. Never mix long strong with standard stroke chambers on the same vehicle.

Brake adjusters
Posted by Joe from Peoria, IL, US on February 8, 2008

Can I use manual adjusters and automatic brake adjusters on the same axle?

NEVER manually adjust automatic brake adjusters. Manual adjustment will not only damage the adjuster, but will also disguise the root cause of a long stroke problem and preclude proper diagnosis and determination of the actual cause of the out of adjustment condition. The only exception would be to permit a driver or technician to manually adjust the brakes to remove the vehicle from the highway, or to enable taking the vehicle to a service facility for proper diagnosis and service.

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