Your Emergency Brake is a Parking Brake


If you are driving a vehicle with an automatic shifting transmission of some sort (ASMT, AT, CVT) you may not even notice whether your emergency brake even works. You may or may not even ever use your emergency brake. Automatic type transmissions have parking palls that, when the transmission is in the park position, physically stop the transmission from rotating and thus will not allow wheels to turn.

By the way that parking pall is not designed to replace the parking brake. Using only park to hold your vehicle in place on steep roads will cause unnecessary wear and tear on your transmission. Repairing a transmission is much more costly than your parking brake system.

On the other hand if you are one of the lucky few still driving a manual transmission equipped vehicle you are very familiar with your emergency brake and its required capabilities.

For clarity’s sake let us decide on a proper nomenclature. Emergency brake is not a proper name. Hand brake is also not proper. The correct name is parking brake because parking brake describes its real function. The parking brake was only designed to hold your vehicle still while parked. It is not designed to stop your vehicle in an emergency situation. It is not always operable by hand. In fact in most vehicles it is pedal operated.

Transport Canada Motor Vehicle Safety uses Technical Standards Document No. 135, Revision 2R to describe Light Vehicle Brake System standards. It is mostly based on a U.S. federal document. Within this document is the required performance characteristics of a parking brake.

In a nutshell a parking brake must be able to hold your fully loaded vehicle stationary on a twenty percent grade uphill or downhill for five minutes. If the brake is hand operated it should require no more than 90 pounds of force on the handle to do this. If pedal operated it will require no more than 112 pounds of force to do this.

A fully loaded vehicle does not include the trailer you are towing. Yes, your parking brake does not have to be able to hold your boat from pulling your truck into the lake at the boat launch while you are loading it.

Like all systems your parking brake system requires maintenance and performance testing. We find many vehicles with parking brakes that easily fail to perform anywhere near what the manufacturer wanted them to do. This is especially true of vehicles with rear disc brake systems that use the drum section of the disc brake rotor as a parking brake.

Most parking brake systems are still mechanical. Ratcheting pedals or handles are used to lever cables connected to fulcrums and pivots that apply force to brake shoes or brake pads. These systems quit functioning as designed when cables stretch and wear, fulcrums and pivots seize, or braking material wears or delaminates.

These systems require service. There are usually adjustment procedures but before spending any time adjusting your mechanic needs to inspect. Every moving part has to move freely. Sometimes this is hard to determine. Many times cables are the culprit for poor performing brake systems. The sheathing inside a cable wears from repeated movement of the braided cable within it. Friction builds up in the cable and the force applied at the pedal is used up by the friction in the cable and does not reach the brake pads or shoes. Only new cables will bring back proper parking brake holding power.

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