Practical Automotive Maintenance: Handbrake
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Handbrake
04.41
| 00:00 | Handbrakes, also known as parking or emergency brakes, are a safety component in all modern vehicles, designed to keep them stationary when parked or provide emergency stopping power if the main braking system fails. |
| 00:12 | The two primary types of handbrake mechanisms are drum and caliper, with more modern vehicles employing an electronically operated version of either. |
| 00:21 | Drum type handbrakes are more commonly found in older vehicles, but are also used in some more modern cars, with a drum incorporated into the hat of the brake disc. |
| 00:31 | Let's look at the drum system first. |
| 00:33 | This uses brake shoes inside a small drum located in the centerpiece or the hat of the rotor, utilizing a threaded mechanical adjuster to ensure correct adjustment. |
| 00:43 | The mechanism is activated by pulling a lever or pressing a pedal, which tensions the cable connected to the brake shoes. |
| 00:49 | Manufacturers specify the correct adjustment to be a light drag of the handbrake shoes to the drum or the rotor. |
| 00:56 | This is of course somewhat ambiguous if you don't know what a light drag should feel like, but we do have some tips on this. |
| 01:02 | When adjusting any mechanical handbrake, it's important to first loosen off the cable adjustment, usually located on the park brake lever itself, which ensures the cable isn't overstretched. |
| 01:13 | From here, a general rule of thumb is to adjust the shoe outward until the rotor can't be turned by hand, and then wind the adjuster backwards three or four clicks or teeth, and this should provide the correct amount of drag, which will allow for quick and correct engagement of the shoes. |
| 01:29 | Once the handbrake shoes have been adjusted correctly, we can then re-tension the cable at the lever until it takes about five to seven clicks to fully engage and hold the weight of the vehicle. |
| 01:39 | Drum handbrakes have a large surface area and therefore are known for their reliability and strong holding power, making them effective for parking on steep inclines, while also being favoured in some circles like grassroots drifting. |
| 01:52 | Although a separate hydraulic caliper is usually going to be preferable once any drift build starts to get more serious. |
| 01:59 | Let's move on and discuss caliper type handbrakes. |
| 02:01 | These are used on vehicles equipped with disc brakes at all four corners, and are operated by applying pressure directly to the brake pads, clamping them against the rotor. |
| 02:10 | The mechanism in these units is a cable-operated lever system with a return spring to release pressure. |
| 02:16 | Adjustment of these mechanisms can vary depending on the design type, with some systems being self-adjusted based on the brake pad wear, and typically only allow for tightening or loosening of the handbrake at the lever or cable itself. |
| 02:29 | Other types of adjustments we may see are a screw on the backside of the piston, sometimes hidden with a protective cap. |
| 02:36 | Adjustment of this system employs a similar theory to the drum type handbrake, requiring tightening until a very light drag on the rotor occurs. |
| 02:44 | Remembering that if we are making adjustments at the brake itself, we first need to loosen the cable at the lever, so it's not too tight. |
| 02:52 | Once the adjustment has been carried out at the brake mechanism, we can again tighten the cable at the lever until 5 to 7 clicks are achieved and the vehicle is able to be held in place solely by the handbrake. |
| 03:02 | The final type of handbrake system used in a large majority of new cars is the electronic park brake. |
| 03:08 | These use the same basic principles of operation as the mechanical types, but rather than being activated by a physical lever, they are electronically activated via a button. |
| 03:18 | When the button is pushed, an electronic motor activates, applying pressure to the brake pads and clamping them tightly onto the brake rotor to hold the vehicle in place. |
| 03:27 | Adjustment of these electronic emergency brakes is initially done with the use of a specialty scan tool. |
| 03:33 | From here the handbrake adjusts automatically as the pad wears down and the piston moves closer to the rotor. |
| 03:39 | It's important to note that when servicing the rear brakes on a vehicle that has an electronic parking brake, this system must be set into service mode before doing so. |
| 03:48 | With each type covered, let's go over the key points found in this module. |
| 03:52 | Handbrakes, also known as emergency or park brakes, are a safety component that keeps a vehicle stationary when parked or slower in emergencies if the main hydraulic system fails. |
| 04:02 | Mechanical systems are either shoe and drum or caliper and pad types, both using a cable connected to a lever operated by the driver. |
| 04:10 | Drum types offer a larger surface area for a strong grip, making them popular in motorsports like drifting. |
| 04:16 | Caliper types also use cables, but clamp pads to a rotor to hold the vehicle. |
| 04:21 | Adjustment for both types involves loosening the cable near the lever, setting the brake component to specification, then re-tensioning. |
| 04:28 | Electronic versions work on the same principle, but use a button to activate motors on the rear caliper, with adjustment and servicing done via a specialty scan tool. |
