Fist Caliper Brake
In contrast to the floating caliper brake, the fist caliper brake comprises only two main components. Because it comprises few components, it weighs less. The fist caliper has minimum space requirement thus allowing the use of axle structures with negative kingpin offset, without the necessity of fitting bulging rims. The guide system is less sensitive to dirt and corrosion than that of the floating caliper.
The way it functions, i.e., build up of pressure, overcoming the clearance and pressing the brake pad against the rotating disc, is similar to that of the floating caliper brake.
Clearance adjustment and compensation for wear are the same as with the fixed caliper and the floating caliper. During braking, the pad is supported by the support and by the housing (fist).
Several fist caliper variations are available from different manufacturers using different guide systems, pad supports and pad removal options.
Instructions for replacing the pads and maintenance work can be found in the garage manuals.
Because of the great variety of fist calipers available, we will not go into more detail.
Fist caliper brake with integrated parking brake (combined brake caliper)
With this type of caliper, the service brake is operated as usual by the hydraulic pressure created in the brake master cylinder. For the parking brake, the force applied to the brake lever is transmitted to a mechanical linkage by the brake cable, whereby the brake piston is brought to the braking position mechanically.
Since the automatic adjustment for these systems is effected by mechanics inside the caliper, it is of the utmost importance, when working on this type of brake (e.g., pad replacement), that the fitting instructions provided by the vehicle or system manufacturer are strictly adhered to. In most cases, it is only possible to return the piston by using special tools.
With some vehicles, the direction of turn required to return the piston varies, depending upon which side of the vehicle the brake caliper is fitted to. In addition to this, some of these combination calipers require a basic setup upon completion of work, in order to ensure trouble-free automatic adjustment.
Electro-mechanical parking brake (EPB)
The principle of these calipers is almost the same as the previously mentioned fist caliper brake with integrated parking brake. In this case, the service brake is also hydraulically operated.
The way in which the parking brake functions however differs. It is applied by means of an electrically operated servo motor integrated into the caliper. To operate the brake, an electrical impulse transmits the command to brake. This command is then executed by the servo motor.
The command to brake can either be given by the driver, by operating a switch or initiated by one of the vehicles control systems (e.g., electronic approach system).
If the brake piston must be moved back for maintenance or repair work, the corresponding fitting instructions given by the brake or vehicle manufacturer must be observed.