Self propelled vegetable harvesting/packing rigs
This SIM draws the attention of inspectors to safety issues and control measures for driverless vegetable harvesting/packing rigs used in the harvesting of fresh produce such as cabbages and cauliflower.
Driverless vegetable harvesting rigs generally consist of a boom type conveying system attached to an agricultural tractor with a trailed packing unit towed behind it. While harvesting, the tractor forward speed is very low (ie creep speed). As the machine progresses through the field it has to be sufficiently slow to allow workers time to harvest the crop and then to place the harvested item on to the conveyor system that transports the produce to the trailed packing unit. Historically, the operation of these machines often involved the tractor driver setting the machine in motion and then vacating the driving position (ie dismounting from the tractor cab).
Once the tractor was set in motion it was effectively "driverless" and operators were required to remount the moving tractor to stop it or to perform other functions such as to change direction etc.
Two companies (Vegetable Harvesting Systems and Keith Collingwood Ltd) are known to supply harvesting rigs/conversion systems to allow control of tractors, at creep speeds, from positions other than the usual driving position. Other manufacturers may exist and users may also attempt to modify their own machines. The Agriculture Waste and Recycling Sector (The Sector) has drawn up the guidelines below setting out reasonably practicable control measures to reduce the main risks associated with driverless operation.
Inspectors may refer to the information below when considering whether the risks have been adequately addressed by users or manufacturers of these machines to ensure safe operation.
In situations where manufacturers or users claim compliance with the requirements below is not reasonable practicable, local Specialist Group (SG) assistance should be sought, together with liaison with the Sector to establish an acceptable alternative.
In cases where more novel approaches are being considered/used (eg remote/radio control) advice should be sought from the Sector. In such situations it is essential that a positive signal from the control device is required to keep the machine running (ie signal failure results in machine shut down).
People at risk from the operation of driverless vegetable harvesting rigs include:
- the driver - at risk of being run over whilst mounting/dismounting a moving tractor
- harvest workers - involved in the harvesting/packaging process at risk of being struck by the moving rig and
- Anyone else approaching a moving rig could be exposed to the same risk while the driver in not in the tractor cab eg a foreman, supervisor, manager etc.
These risks need to be considered by manufacturers and by users.
The Sector considers the following to be the basic requirements of the control system to ensure the safety of persons involved in operating these rigs and to satisfy the relevant essential health and safety requirements of the Supply of Machinery (Safety) Regulations 2008 and should be addressed by manufacturers/users:
Issues to be addressed by manufacturers and users:
- (i) operating speed of the tractor not to exceed 1000 metres/hour.
- (ii) one set of controls outside the tractor cab to control the following tractor functions:
- (a) stop;
- (b) start;
- (c) brake;
- (d) steering.
- (iii) controls to be located so that they are:
- (a) under the control of one competent person only ;
- (b) positioned behind the boom. It may be acceptable to place the controls in front of the boom to give the operator a clear view of the rig. However, this is only acceptable if operation of the control to start the tractor does not result in a sudden movement liable to cause injury.
- (c) in a place giving a clear view of the tractor/trailer access/mounting points and the area in front of the tractor. Where this is not possible there should be a system for communicating between the packing trailer and the operator to ensure workers are made aware the rig is about to move eg an audible or visual warning device;
- (d) not easily detachable from the machine;
- (iv) fitted with emergency stops
These should be fitted on the boom and also readily accessible to person(s) on the rig (and on the packing trailer), Requirements for stopping devices:
- (a) twist reset type
- (b) connected so that electrical supply is required to keep fuel supply on;
- (v) electrical and hydraulic systems controlling safety related systems to fail safe, ie to stop tractor;
- (vi) a trip bar in front of the tractor:
- (a) mounted to protect workers from danger eg across the full width of the tractor including the wheels or in front of the tractor wheels. The bar should not exceed a maximum height above the ground of 800 mm;
- (b) fitted with two switches installed in positive and negative modes. In a single circuit to the fuel shut off device. Valves and switches used must be suitable for safety applications and for the environment in which they are to be used (eg protection against weather, vibration, etc);
- (vii) an inhibitor switch to the gear selector so remote operation is only achieved in low gear range;
- (viii) the machine's stopping performance to be adequate to prevent serious injury.
- The machine should come to a halt as quickly as is reasonably practicable when an emergency stop, other stopping devices or trip bar are operated
- (ix) all external controls to be isolated when in folded/transport mode and relevant internal controls to be positioned/isolated to prevent inadvertent operation during transport;
- (x) sequential boom folding to ensure that the boom does not exceed a height of 4 m above ground level when folding from/to the transport position. This should prevent a risk of contact with overhead electricity power lines (OHPLs).
Additional issues to be addressed by the user:
- (i) risk assessment should include consideration of any relevant site/field conditions (eg the ability to stop the rig on sloping ground);
- (ii) access to/egress from the tractor/rig to be carried out when the unit is stationary and not to be permitted when the unit is moving;
- (iii) provision of adequate information, instructions and training for workers using the machine, including for casual or seasonal staff.
- (iv) where necessary to make further appropriate arrangements to ensure the safety of workers who have little or no knowledge of the English language.
- The Supply of Machinery (Safety) Regulations 2008
- New machinery supply web pages
For further advice please contact Agriculture and Food Sector – Safety team, Nottingham.