top of page

Put on the Brakes

Spring has officially sprung, according to the 2017 calendar! As one season ends and another begins, certain configurations of trucks and trailers come out of hibernation when the warmer begins. While semi-tractor trailers stay busy all year long, the arrival of spring welcomes the rebirthing of construction and landscaping trucks, and the trailers they tow. Similar to the trucks, these trailers need brakes to stop.  Most truckers who are put out-of-service roadside can attribute their status to bad brakes. Let this article serve as a reminder to put the brakes on bad brakes.

All vehicles needs brakes to stop, and most trailers needs brakes as well with a few exceptions. The larger trailers pulled by semi tractors operate on air brakes. It’s a great system because it is designed to be fail safe. If the brake line is severed or the air compressor fails, air is released from within the braking system and the spring brakes ‘pop’ bringing the trailer to a stop.

Air brakes are a great thing to have in case a trailer separates from the tractor while driving down the road. Smaller trailers generally do not operate on air brakes, but rather electricity.  If the trailer being towed has a gross weight (on the scale) exceeding 5,000 pounds, three different braking components are required.

Service Brakes

When the driver of a semi-tractor trailer, or a truck trailer combination applies the brakes, the service brakes on the trailer must automatically activate as well.  This is required under law in the Illinois Vehicle Code which reads:

625 ILCS 5/12-301(a):

Every motor vehicle, expanded-use antique vehicle, trailer, pole trailer or semitrailer, sold in this State or operated upon the highways shall be equipped with service brakes upon all wheels of every such vehicle, except any motor-driven cycle, and except that any trailer, pole trailer or semitrailer 3,000 pounds gross weight or less need not be equipped with brakes, and except that any trailer or semitrailer with gross weight over 3,000 pounds but under 5,001 pounds need be equipped with brakes on only one wheel on each side of the vehicle.

If a truck is towing a trailer with a gross weight greater than 5,000 pounds, the trailer must have full service brakes on every wheel.

Independent Braking Control

Every trailer or semitrailer of a gross weight of over 3,000 pounds, when operated upon a highway must be equipped with brakes adequate to control the movement of, to stop and to hold such vehicle, and designed so as to be operable by the driver of the towing vehicle from its cab.

In semi-tractor trailers this braking control is commonly referred to as a “johnny bar”, or “trolley bar”.  It is a lever inside the cab on the steering column which gives the driver the ability to independently control the brakes of the trailer without using the service brakes of the tractor. In smaller truck trailer combinations, this control is built into a proportional trailer brake controller. This control box allows the driver to manually set the intensity of the brakes, and to engage the trailer brake without activating the truck’s service brakes.

Emergency Breakaway System

As mentioned previously, most semi-tractor trailers operate on air brakes. If the braking system fails, the trailer brakes automatically engage as there is inadequate air pressure to compress the spring brakes. In trailers which operate on electric brakes, the breakaway system operates differently.

Such brakes must be so designed and connected that in case of an accidental breakaway of a towed vehicle over 5,000 pounds, the brakes are automatically applied.


The brakes must be designed to ensure that, in case of an accidental breakaway of a towed boat trailer over 5,000 pounds, the brakes are automatically applied, one оf thе trеndѕ among drivers is thаt a person thаt has a hаbіt оf brаkіng hаrd іѕ mоrе lіkеlу tо be іnvоlvеd in accidents thаn ѕоmеоnе who does nоt brake hаrd.

Onе оf thе mоѕt соmmоn tуреѕ оf іnѕurаnсе сlаіmѕ іѕ rear еnd collisions. Inѕurаnсе соmраnіеѕ ѕtаtе thаt ѕаfе drіvеrѕ wіll allow an average оf 39% mоrе time tо ѕtор and 32% mоrе dіѕtаnсе. In addition there іѕ a large vаrіаnсе in hоw drіvеrѕ brake, important to learn in order to avoid getting in an accident and in legal problems. If you are involved in an accident caused by drunk driving then you will be in need of legal help, consider contacting a truck accident attorney for their service.

For the electric braking trailers, a battery is installed on the trailer which serves as a power source to activate the trailer brakes and prevent the trailer from running wild in the event of a breakaway. A cable is connected to the braking apparatus of the trailer and the other end is connected to the power unit.  During a breakaway event, the cable pulls the pin away from the trailer, which completes the circuit, allowing energy from the battery to automatically apply the brakes.

Faulty brakes can be costly. As the construction and landscaping season begins, take the time to make sure a driver can apply the brakes should an emergency arise.

46 views0 comments

Recent Posts

See All


bottom of page