Truck Air Brake System Maintenance

Truck Air Brake System Maintenance
The following is a guest mail by one of our resident Diesel Experts, Jeff Celentano !
Air brake sustenance is a critical part of a hand truck, specially during the northern winter months when air lines are prone to freezing. In this post, we will cover the details of proper air brake sustenance, adenine well as address some myths regarding using alcohol as a form of antifreeze .

A few Guidelines to Follow

Each US State has particular guidelines for operating a vehicle with air brakes, and you should be mindful of the guidelines pertaining to your state. however, there are some general steps and guidelines you can follow .

  • Make sure the minimum operating pressure for a vehicle airbrake system is no less than 85 PSI for a bus and 100 PSIfor a truck.
  • control that it takes no longer than two minutes for air pressure to rise from 85

    pounds per square inch to 100 psi at 600 to 900 revolutions per minute. This is called the tune coerce buildup rate.

  • confirm that the correct cut-out governor atmospheric pressure for the vent compressor is between 120 psi and 135 psi. cut-in pressure is 20 psi to 25 pounds per square inch below cut-out pressure .

additionally, you should always be on the lookout for urine in the air-brake system. This is particularly true during the winter months. Water in the air-brake organization is typically a by-product of condense atmosphere, and when it freezes up, it can block atmosphere from reaching the brake mechanism. When air out is blocked in the organization, this can cause the bicycle to lock up .
Truck Air Brake System Maintenance
To prevent this, many modern air-brake systems use automatic rifle drain valves in each air tank that purge automatically.However, another problem that you may commonly see, which is breeze couplers. When the arctic seals become careworn or chemically dried out, air can escape. While air compressors can typically overcome little leaks, pushing the compressors besides hard will ultimately lead to bankruptcy and other issues all for an over the counter $ 2.59 cent separate that is frequently very overlook .
This leads to another problem — Placing alcohol into an air-brake arrangement. This can be a serious venture. Alcohol, specially acetone, will eat rubbers and plastics. What do you think your seals made of ? Rubber. The alcohol will finally eat through the seals and cause a draw of problems for you .
fortunately, seeing a complete brake bankruptcy on a trailer truck is not coarse. today ’ randomness modern base hit systems such as double vent brake systems and anti-lock brakes ( ABS ) serve with brake system failures. If one organization will fail, the second base system should however work. however, if you are running alcohol in your air brake system, plus going through a bunch of internal-combustion engine and bamboozle, well letsjust say your secondary air system could easily fail angstrom well .

Air Brake maintenance

Dual system diagram
Air bracken maintenance is critical. here is a quick checklist of things to check your air travel brake organization for .

  • Checking for valve failure in the primary and secondary circuits. Valve failures can compromise the system, so check these by opening the drain valve on the wet tank.
  • Check for soil, debris and salt build up on the glad hands.

  • I nspect any rubber boots and seals for abdominal connecters and besides

    visit for any signs of wear.

  • confirm that the push rods and mire adjusters are properly operating, because these are essential to maintaining the adaptation of the brake shoes in relation to the drum.

  • Inspect the push rod actuation from the brake chambers, particularly any broken or weak springs.
  • Inspect the parking brakes for leaks in each chamber, or damaged components.

Alcohol and Alcohol Evaporators

Let ’ s talk a little more about alcohol in truck atmosphere bracken organization. Putting alcohol into the vent brake system is a common method acting that some consumption to prevent brake lineage freezing. Methyl alcohol vapor is typically introduced to the vent system, and compressed air travels from the compressor to the air tank. The methyl alcohol will help to prevent freeze .
While this has temp benefits, it besides comes with a range of issues. As we mentioned earlier, harsh alcohol like acetone can and will wear out or even eat through rubbers and plastics. While you might be preventing brake freeze, you ’ ll be introducing your air brake system to a rate of other complications down the road .
Alcohol doesn ’ metric ton very feed acrylics, but it can dissolve the glues and solvents used to hold acrylic pieces together. It ’ s not unheard of to see acrylic reservoirs falling apart and leaking, due to alcohol dissolving the solvents .
furthermore, alcohol can besides choke the publicize supplies when used falsely. Some air brake systems have an alcohol evaporator for the purpose of putting alcohol into the air system. This is an older engineering that inactive works and will normally have an alcohol container specifically for pouring alcohol into .
even if you use an alcohol evaporator in your vent bracken system, it is however absolutely all-important to perform daily air brake system sustenance. This includes cooler drain, for eliminating urine and oil. The exception hera is unless the system has automatic drain valves but don ’ thyroxine believe those wholly. They are mechanical components, and mechanical things fail every day .

De- Icers and Alcohol

Trailer alcohol injector
For the most part, you should pour approved deicers only into the emergency side of an air travel system ( the red glad pass side ). For example, the manufacturer might approve methyl alcohol, but not approve isopropyl or ethylene diol .
This is because ethylene ethylene glycol can swell the o-rings within brake valves and break down the lubricants which protect the internal pistons that control the air flow. The early issue Is that people frequently don ’ thyroxine know or make a err and pour the fluids into the blue glad hand. The fluid will only sit on circus tent systems air brake valves. This could prevent the valve from orifice, which is necessity for allowing tune to pass .
2+2 Air Line Anti-freeze
Alcohol needs a path to travel. If you don ’ t first drain the publicize tank, you could pour gallons of alcohol into the front, and it ’ s not going anywhere. It will just go to the lowest item in the air line and sit there, useless. Remember that it ’ s not the alcohol itself that thaws flash-frozen components in the air-brake system, but the alcohol vapor .
A little bite will go a farseeing way, such as an eighth of an snow leopard, preferably than half a jug. furthermore, if you ’ rhenium considering putting alcohol into your air-brake organization, you should actually beasking yourself why you even have moisture in the air-brake arrangement to begin with .
In retread, using alcohol in an air-brake system may be a impermanent solution, but it does not address the very problem .

Addressing the real problem

Because it ’ s the moisture in the air out that freezes, and ice is what jams the inner workings of your brake valve, you need to combat air moisture in the first target .
Air dryers are however not, but should be, standard equipment. These motivation to be maintained again. One of the worst things that can happen with atmosphere dryers is progressive damage. By not performing dim-witted checks and regular alimony, a simple emergence can turn expensive very quickly. For example, running your air dry over a long time period of time means that humble amounts of carbon and oil contaminates are pushed through the compressor home components. This includes the piston rings and coating inside of the cartridge. If your magazine fails, you could find yourself with millions of bantam desiccant balls invading every column inch of your trucks air brake system. This is the slow death, and costly haunt, of your entire air brake system .
During annual winter maintenance, it ’ sulfur recommended to replace the atmosphere dry ’ second desiccant. These cartridges are filled with a water-absorbing material, but not all are created peer. Spend a little excess money for high-quality cartridges, as cheaper materials are prone to breakdown on the subcontract. Its not about the cheapest up-front cost, its about total monetary value of ownership .
Cheap publicize dryers will besides run hot, which results in a breakdown of their desiccant which will then feed through the breeze system. This will end up clogging orifices within the ABS valve and destroy your brakes .

Don ’ t Always Believe Your Air Gauges

Low Air
A glance at the air out gauge can ’ thymine be your only trial of air issue. If a line collapses or ice is lodged, air can still get in but will become trapped, which will inflate the pressure, giving you a false take of your true breeze supplies .
During pre-trip check or fomite inspection, it ’ s easy to perform this test while sitting in the driver ’ s seat. Pump the brake pedal until you hear the warn buzzer – then watch the needle climb up again. When you hear the breeze dryer blowing off, how far up does it go ?
If it only climbs up to around 105 pounds per square inch, you don ’ t have enough air. You should be able to do around seven full brake applications without hearing the buzzer admonitory, anything less than that is a serious trouble .

Be careful With a flashlight

This is narrative time. In the early eighties I was working a second job at night to feed my Alcohol Drag Bike addiction. I got a job at a major fleets trailer patronize where we refurbished trailers that were very particular for breweries and were equipped with electric floors. The things we build so american can get its beer .
A preview was dropped due to the brakes being locked up on a recurrence tripper and the driver said he dragged it to the yard and left it in the drive lane. We had a dawdler yard that was about 1/8 of a mile in duration. This is January in Upstate NY around 2 am withtemperatures good below zero .
I was trying to retrieve a trailer using the yard horse, but the brakes were flash-frozen solid. I crawled under with a torch and started heating up the breeze tanks and valves to thaw frozen brake valves. What I didn ’ deoxythymidine monophosphate know was that the air out cooler was full of alcohol. Well, the tank exploded with such push it blew a hole through the floor of the trailer and bend floor brace .
As for me I lost the listen in both ears for a few weeks and felt that I cheated death. My friends that knew me back then say I never recovered, despite what the doctors said. If that tank blows the other manner towards me, I wouldn ’ deoxythymidine monophosphate be here right now. The example I learned is that alcohol belongs in beverages and Drag bikes should run on ten percentage nitro. I promptly converted mine. This is a awful practice, and if you ’ re doing it please stop, I was lucky.

Final Tips

At the end of the day, you should go through a checklist of things to maintain. This includes bleeding the tune from your air-brake organization, monitoring for body of water in the system, checking the automatic rifle drain valves, and everything else mentioned. Be safe out there !

About Jeff

Jeff Before getting into Heavy trucks in 2001, I worked as an Automotive Mechanic for Cadillac during the day Spent a few years as a trailer automobile mechanic and a factory Trained Suzuki / Kawasaki Motorcycle Mechanic at nox and weekends unless that weekend involved Drag racing my Motorcycle.
Before joining Diesel Laptops, I spent eighteen years working my way up in a Navistar Dealership. Nine of those years were working in back counterparts looking up and suppling diesel technicians with parts to repair trucks. I moved into service as the dealer Warranty writer and file clerk, Next was Shop Foremen then Service Manager .

reference :
Category : Car Brakes