Big Rig Basics

John Baxter | December 01, 2010

Staying Connected

Carrying spare seals with you is a good idea.

Gladhand maintenance is critical to keeping the air brake system in working order

The gladhands allow the air brake system of any tractor to be disconnected from one trailer and connected to another. The gladhands connect downstream of the dryer, so failing to care for them will allow moisture into the system and cause trouble. The gladhands have rubber seals that enable them to seal tight even though constantly being turned against one another. The seals eventually wear out because of the turning action and because rubber naturally deteriorates. Take care of the gladhand seals, and you’ll find your air compressor and air dryer desiccant package will last longer, and you’ll get better braking.

Ed Geiger, an owner-operator leased to FedEx Ground, helped us with information about how he keeps his gladhand seals in good condition.

These seals can start to leak at any time, so it’s smart to carry some spares with you, as Geiger does. He says you’ll hear leaks inside the cab from outside when disengaging the parking brake or applying the service brakes. You can sometimes also hear leaks at the air valves in the dash. Leaks should be fixed right away because they will increase air consumption. This means deterioration of the desiccant in the dryer, resulting in a need for service. Leaks also mean much more wear on the air compressor.

Other preventive practices including always hooking the gladhands, sealed, to their holding brackets when dropping a trailer. When they’re not kept sealed, moisture will damage brake system parts and, in winter, can cause freeze-up of the service or parking brakes.


1. Cracks or pieces broken out indicate it’s time to replace the gladhands.







2. The parking brake lines and fittings are coded red, while the service brakes are blue. When using colored seals, put the proper color in each type of gladhand connector.






3. The two main types of seals include those with a convex outside surface and flat ones. The seal type varies with the type of gladhand, though there are some universal gladhands. Note that the sealing surface is to the right on the convex type seal, and to the left on the flat-surface seal. The portion that goes inside the gladhand to hold the seal in place is larger than the sealing portion on flat-faced seals, but smaller on convex type seals.



4. Seals are easily removed by prying them out gently with a screwdriver. Be careful not to probe too far or pry too hard and score gladhand surface itself with the screwdriver.






5. This is how the glandhand will look with the seal removed. If there is any evidence of dirt or rubber sticking to the groove in the air hole where the seal is installed, use a paper towel or clean rag to wipe it clean.





6. Install the new seal by positioning the mounting half of the seal toward the air hole in the gladhand, and aligning it squarely with the hole. Then press inward all around on the sealing surface to force the mounting half of the seal to lock into the groove in the gladhand all the way around. Ron Fay, product manager at Phillips, says to turn the seal around a bit once it’s in place to make sure it is properly seated.



7. This is how a flat seal will look when installed.