Basic risk assessment example: Flail hedge cutter (tractor-mounted)
The following risk assessment is intended as a guide to the steps that a manufacturer, or designer, should take in gathering information to evaluate risks associated with a machine before it is built.
This example lists typical hazards associated with the use of a tractor-mounted flail hedge cutter and the likely source of each identified hazard. An assessment enables a manufacturer/designer decide what steps need to be taken to eliminate or minimise risks to operators and others.
| Hazard | Location/source | Safety measures/comments |
|---|---|---|
| Entanglement | Drive shafts (including PTO), rotating shafts of head | Shaft guards, stand off guard for head, to relevant BS/CEN standard |
| Draw-in/trapping | Belt and pulley/chain and sprocket drives (when/if present) | Guard drives/run on points to relevant BS/CEN standard |
| Impact | Machine head or arm against people or tractor | Limit movement in tractor zone |
| Stab/puncture | By ejected debris | Design head to direct debris away from tractor; provide/specify guards for cab |
| Ejection of parts | Flails | Design head cowl to direct ejected flails away from tractor. breakaway head and freely rotating flails reduce flail ejection; design to prevent head touching ground |
| Unexpected start up | When tractor starts | Control levers to automatically return to neutral (either when released or when power disengaged depending on operational requirements) |
| Loss of stability | When free standing (out of use) | Design for free-standing balance; provision of supplementary stands fitted to machine |
| Stability loss when mounted on tractor | When arm is at maximum reach | Weight distribution/recommend tractor ballast weight range |
| Crushing | Arm movement/articulation | Design for adequate clearance in fully closed position |
| Shearing | Arm movement/articulation | Design adequate clearance for articulation |
| Break up during operation | Machine structure and cutting head | Selection of materials with appropriate quality assurance; design of cowl on head to contain ejected parts |
| Failure of control system (unexpected overrun) | During stopping of hedge cutter or tractor | Design hydraulic controls to fail safe; fit overrun alarm and braking system. |
| Cutting/severing | Sharp corners etc. | Design exposed parts to have smooth/rounded corners etc |
| High pressure fluid injection | From hydraulic system | Manufacture to relevant standard; route hoses to avoid chaffing; use of pressure relief valves |
| Noise/vibration | Measure and reduce as low as practical and when risk is likely | |
| Errors of fitting or dismounting | Before or after cutting activities | Design couplings for specific application; clear instruction manual |
| Ergonomic hazard – position of controls | Operation of cutter hydraulic remote controls | Allow adequate control connection flexibility to enable operator preference when locating controls |
| Unexpected arm movement during transport | Impact against people or tractor | Isolators for hydraulic controls; locking pins to hold arm in transport position |
| Slip/trip/fall | From machine during maintenance | Design for access from ground level; instruct for safe access if design not possible |
| Control design/marking | Manufacture to relevant standard | |
| Electric shock | From contact with overhead power lines | Warning signs on machine and in instruction manual (include details of machine height/reach) |