We recently read a question on a trucking forum from a driver who was having trouble with his brakes locking up. He mentioned that the problem did not occur when he was carrying a full or near-full load. Yet, when he didn’t have the added weight, the brakes would lock up and would cause a temporary loss of control of the trailer. Obviously, this is a very dangerous situation that drivers do not want to have to contend with. It is also a strong indication that something is not right in the brake assembly.
To be more specific, there is likely a problem with the S-cam bushing.
S-cam drum brakes are very common on tractor trailers these days. Tractor trailer technicians are highly familiar with them, and they know what maintenance must be done to ensure that the brakes operate correctly when needed, but also to prevent the locking sensation that the driver above was experiencing.
There are tools available that can help DIYers do their own brake maintenance. Yet, it is truly essential to be very familiar with the braking assembly. There are some manual adjustments that an inexperienced individual might believe to be helpful, but that could cause more harm that good. It is also important to be familiar with the individual pieces and components of the braking system.
In the situation above, it is very likely that the driver (or his inexperienced technician) replaced the S-cam bushing, but when doing so, the wrong replacement was selected. Because all of the components of the braking system are so interdependent, one wrong piece can cause serious malfunction. In this case, that could mean that the brakes lock up and the trailer is whipped about.
On any vehicle, the brakes are important, but with the massive amount of weight carried by a tractor trailer, this system is asked to bear a very tremendous load. When maintenance and repairs are not properly executed, lives are put at great risk.
Categorised in: Brakes
This post was written by J and M