Videoplayer - SyA7/SyR7

General Information

SYNACT® - The brake for heavy commercial vehicles
Description of operation

Functional and Visual Check

Inspection Points
Wear Check of Brake Pads and Brake Discs
Adjuster Function Check
Caliper Movement and Running Clearance Check
Bearing clearance check in the area of the Floating Bearing
Sealing Elements Check

Service and Maintenance Work

Brake Identification and Service Kits
Replacement of Brake Pads without ACR and without Wear Indicator
Replacement of Brake Pads without ACR but with Wear Indicator
Replacement of Brake Pads with ACR but without Wear Indicator
Replacement of Brake Pads with ACR and with Wear Indicator
Tappet and Boot Assemblies and Inner Seals replacement
Caliper Replacement
Caliper Bearings Replacement
Carrier Replacement
Knorr-Bremse Brake Actuator Replacement
Knorr-Bremse Spring Brake Actuator Replacement

Pneumatic Disc Brakes SyA7/SyR7 - Service Animations

Service animations for the maintenance of SyA7 and SyR7 pneumatic disc brakes. The individual service steps can be selected directly, subtitles can be displayed or different languages can be selected. Printable document: Y458802

Note: The safety advice listed below is applicable to general service and diagnostic work on braking systems. Also observe any recommendations from the axle or vehicle manufacturer concerning towing, jacking-up and securing the vehicle.

CAUTION: Knorr-Bremse is not liable for any costs and damage caused by improper installation and use of Knorr-Bremse aftermarket products, in particular in the event of (i) use in non-approved applications and/or use in non-compliance with the technical specifications and installation instructions, (ii) incorrect installation or removal of Knorr-Bremse aftermarket products and (iii) failure to observe instructions on the use of tools.

In addition to product-specific installation and hazard warnings, the following precautions and additional hazard warnings must be observed before and during work on and around compressed air systems:

Always wear safety glasses when working with air pressure.
Never exceed the vehicle manufacturer’s recommended air pressures.
Never look into air jets or direct them at anyone.
Never connect or disconnect a hose or line containing pressure; it may whip as air escapes.
When removing or servicing a product, ensure all pressure related to the specific system it is contained in has been depleted to 0 bar. Be aware that if the vehicle is equipped with an air dryer system, it can also contain air pressure along with its purge reservoir, if fitted, even after pressure has been drained from the other reservoirs.
If it is necessary to drain the air pressure from reservoirs, etc., keep away from brake actuator push rods and levers since they may move as system pressure drops. On vehicles fitted with air suspension, it is advised when undertaking such work, to support the chassis from sudden lowering and therefore prevent any possibility of being trapped between the chassis and axle or ground.
Park the vehicle on a level surface, apply the parking brakes, and always chock the wheels as depleting vehicle air system pressure may cause the vehicle to roll.
When working under or around the vehicle, and particularly when working in the engine compartment, the engine should be shut off and the battery disconnected. Where circumstances require that the engine be running, EXTREME CAUTION should be taken to prevent personal injury resulting from contact with moving, rotating, leaking, heated or electrically charged components. Additionally, it is advisable to place a clear sign on or near the steering wheel advising that there is work in progress on the vehicle.
When working on vehicles equipped with air suspension, to guard against injury due to unexpected downward movement of the chassis caused by sudden pressure loss in the suspension system, ensure that the vehicle chassis is mechanically supported with a ‘prop’ between the chassis and the axle or between the chassis and the ground.
Examine all pipework for signs of kinks, dents, abrasion, drying out or overheating. Be aware that kinks in pipework may result in air pressure being trapped in the pipework and associated equipment. Replacement hardware, tubing, hose, fittings, etc. must be of equivalent size, type and strength as original equipment and be designed specifically for such applications and systems. Check the attachment of all pipework; it should be installed so that it cannot abrade or be subjected to excessive heat. Only use tools specially designed for cutting pipes in order to prevent incorrect cutting and, in particular, to avoid shavings remaining in the pipes or other impurities which may later lead to leaking connections and subsequent malfunctions of the system.
Components with stripped threads or damaged/corroded parts must be replaced completely. Do not attempt repairs requiring machining or welding unless specifically stated and approved by the vehicle or component manufacturer.
Never attempt to install, remove, disassemble or assemble a device until you have read and thoroughly understood the recommended procedures. Some units contain powerful springs and injury can result if not properly dismantled and reassembled. Use only the correct tools and observe all precautions pertaining to use of those tools.
Before removing any device note its position and the connections of all pipework so that the replacement/serviced device can be properly installed. Ensure that adequate support or assistance is provided for the removal/installation of heavy items.
We highly recommend to use only genuine replacement parts, components, and kits as supplied by Knorr-Bremse or the vehicle manufacturer containing original Knorr-Bremse parts. Knorr-Bremse will not be liable for any issues arising from the usage of non-Knorr-Bremse products. Only use the recommended tools as specified in related Knorr-Bremse instructions.
The serviced or replaced product must be checked for correct function and effectiveness.
If products have been dismantled, serviced or replaced, whose performance could affect braking performance or system behaviour, this should be checked on a roller dynamometer. Bear in mind that a lower performance may be experienced during the bedding-in phase if new brake pads/linings and/or brake discs/drums have been fitted.
The use of impact screwdrivers or impact wrenches in conjunction with Knorr-Bremse service tools for air disc brakes is not permitted. The service tools are not designed for such use. It is likely that the tools or the vehicle will be damaged and there is a serious risk of injury – see Caution above.
Do not use compressed air to clean the disc brake. Avoid air contamination of brake dust.
Prior to returning the vehicle to service, make certain that all components and the complete brake systems are leak free and restored to their proper operating condition.
During service work on vehicles with electronic parking brake, service or parking brake, or bus stop temporary hold brake, the brake system must be set to service and maintenance mode. Please also observe the instructions of the vehicle manufacturer.

Disposal of Waste Equipment by Business Users in the European Union

This symbol on the product, packaging or in user instructions, indicates that this product must not be disposed of with other general waste. Instead, it is your responsibility to dispose of the waste electrical and electronic parts of this product by handing them over to a company or organisation authorised for the recycling of waste electrical and electronic equipment. For more information about arrangements for waste equipment disposal please contact your Knorr-Bremse distributor or local Knorr-Bremse representative.

The use of impact screwdrivers / impact wrenches in conjunction with Knorr-Bremse service tools for air disc brakes is not permitted. The service tools are not designed for such use.
Never turn the Adjuster (23) without Shear Adapter (61). If the given shear point of the Shear Adapter (61) is reached, the adapter will fail. Try again using a brand new shear adapter. If the adapter fails a second time, the whole caliper will need replacing due to internal damage. Do not use an open-ended spanner on the adapter as this could damage it.
Attention: Risk of injury. Knorr-Bremse accepts no liability for damage or injury resulting from negligence; any damage to service tools resulting from such actions will void all warranty.

Safety Instructions for Service Work and Repair Work
Observe relevant safety instructions for service work and repair work on commercial vehicles, especially for jacking up and securing the vehicle.
Use only genuine Knorr-Bremse parts.
Before starting service work, ensure the service brake and parking brake, as well as the bus stop temporary hold brake, if fitted, are not applied and that the vehicle cannot roll away.

Please follow service manual instructions and adhere to the wear limits of the pads and the discs (see Section 5.1).
Use only recommended tools (see Section 2.1).
Tighten bolts and nuts to the prescribed torque values (see Section 2.4).
Screw threads and tapped holes must be free of lubrication and residuals of thread locking products.

After re-fitting a wheel according to the vehicle manufacturer’s recommendations, ensure that there is sufficient clearance between the tyre inflation valve, the caliper and the wheel rim, to avoid damage to the valve and the wheel.

After any service work: Check the brake performance and the system behaviour on a roller dynamometer. Check function and effectiveness. Bear in mind that a lower performance can appear during the breaking-in phase of the brake pads and/or the brake disc.