Brakes, steering and safety systems
The systems that stop the machine and keep the driver safe
Brakes, steering and safety systems are what determine whether a machine can be stopped and controlled and whether the driver is protected if something goes wrong. An error here is rarely just a downtime — it can cost lives. Therefore these systems are subject to stricter requirements and you must be able to inspect and troubleshoot them without compromise.
§Brake system types
Heavy machinery often uses more robust brakes than cars. Many contractor and farm machines have oil-cooled disk brakes that are enclosed and run in an oil bath so they can withstand hard and continuous loading without overheating. Others use disc or drum brakes. The brakes can be hydraulically, pneumatically or mechanically operated.
- 01Service brake: the brake the driver uses for daily braking.
- 02Parking brake: keeps the machine at rest when it is parked.
- 03Emergency brake: an independent system that can stop the machine if the service brake fails.
- 04Engine brake/retarder: helps keep speed down when driving downhill without wearing the service brake.
§Control systems
Most heavy machines have hydraulic power steering and many earthmoving machines steer by 'breaking' in the middle (articulated steering/jointed steering) rather than turning the wheels. Steering is safety-critical: a leak or an air bubble in the steering circuit can make the machine hard or impossible to steer. Some machines have an emergency steering pump that provides steering if the main pump fails.
§Passive safety: ROPS and FOPS
The operator's cage protects the operator in case of accident. ROPS (Roll-Over Protective Structure) is a rollbar/cab that protects in case of rollover, and FOPS (Falling-Object Protective Structure) protects against falling objects. These structures are type-approved, and must not be welded into, drilled into, or modified, as this voids the approval and thus the protection. A rolled-over machine with intact ROPS and secured operator is often the difference between a scratch and a fatal accident.
§Active safety systems
Modern machines have a number of systems that prevent unintended movement: seat contact that stops functions if the driver leaves the seat, control lock in transport position, dead-man button/activation lever and start block that only allows start in neutral. Understand them as part of safety — never disable them to make the work 'easier'.
§Inspection and troubleshooting
- 01Check brake effect, pedal travel and any brake pressure to specification.
- 02Look for leaks in the brake and steering circuit and check oil level.
- 03Test the parking and emergency brake on a safe, level surface.
- 04Test that seat contact, operating lock and start lock work as they should.
- 05Check cab guards, belts and shields for damage.
Brakes, steering and safety systems are where 'good enough' does not exist. Follow manufacturer's instructions leave approved designs alone and never hand over a machine with a safety system out of function.