Gatherer stitcher trimmers
Serious accidents have resulted at gatherer stitcher trimmers (GSTs), collator stitcher trimmers and gang stitcher trimmers, in particular through contact with the trimmer knives and through the incorrect operation of wander lead controls.
Fixed and interlocked guards should be provided for dangerous parts of the gatherer feed stations. Interlocked guards normally take the form of hinged perspex lift-up guards, either for individual feed stations, or as a single guard covering all the feed stations. Interlocking is normally achieved through the use of positively operating cam switches. Users should be encouraged to carry out regular guard checks to ensure safety is maintained. Under no circumstances should interlocked switches be removed or defeated.
Problems can occur where single cam switches are provided for single guards covering all feed stations due to the cam moving out of alignment and allowing operation of the stations with the guards raised. In such circumstances upgrading to provide a second cam switch operating in the opposite mode, mounted by the side of the original switch, would achieve a higher standard of safety and should be considered.
Access should not be possible through or around guards to dangerous parts. BS EN 294:1992 safety standards should be applied.
Fixed and or interlocked guards should be provided for dangerous parts associated with the stitcher section, including the stitching heads. Guarding may take Fixed and or interlocked guards should be provided for dangerous parts associated with the stitcher section, including the stitching heads. Guarding may take the form of a single pivot Perspex guard fitted with a single cam-operated interlock switch or a mechanical/electrical device. Any interlock switch should operate in the positive mode. Access should not be possible through or around guards to dangerous parts. It is strongly advisable to introduce a formal guard safety check system and maintain all records.
The trimmer section usually consists of three guillotine blades or knives (the head and tail knives and the forage knife), which reciprocate automatically throughout the run. Guarding for the blades and other dangerous parts is essential, and may take the form of a sliding tunnel guard or a large pivot type guard split into two sections hinged at the middle. Access to the blades with the guards open will be required for knife changing and adjustment. Again, these guards should form part of the guard check system.
The guards should be interlocked by means of positively acting interlock switches which will normally be cam operated. Care must be taken to ensure that the cams do not move out of adjustment; upgrading as outlined above may be appropriate. Opening of the guards while the blades are in motion must stop dangerous movement before a hand can reach a danger point.
Fixed guarding is not usually a suitable alternative to interlocked guards due to the need for frequent access. Openings in the guards, including feed and delivery openings, should not allow access to dangerous parts. Where this is found to be possible through the delivery or other openings, guarding should be upgraded to prevent it.
Controls for setting and adjustment (including wander leads)
Local two-hand ‘hold-to– run’ controls or a two hand ‘hold to run’ wander lead can be provided which allows operation of the GST with one guard open. These are only considered appropriate if the following conditions are met:
- where two-hand controls are provided they should be checked to ensure the controls require simultaneous operation in line with BS EN 60204:1993 and that the controls are suitably positioned to prevent spanning by one hand. Controls that fail to meet the standards outlined above should be upgraded
- with the gatherer/feeder station or the stitcher guard open (but not the trimmer guard) the machine may run at speeds approaching 25m min although the speed should be set as low as possible
- setting, maintenance and knife change operations with the trimmer guards open should be a one-person operation carried out by a trained operator. The operator should be in control of any inch or pendant controls. Accidents have occurred when two operators have been working together and one has operated the wander lead while the other has had their hands in the trimmer section. The two-hand controls or wander leads should not permit running or jogging of the trimmer section with the guards open although a single stroke is permissible.
- where operation of the knives is not restricted to a single cut with the trimmer guards open, machines should be designed to allow necessary running adjustments with guards closed.
Transmission machinery should be fenced securely. Standards for fixed or interlocked guarding should take account of the frequency of access. Manufacturers should be encouraged to design machines which do not require access to dangerous transmission machinery on a frequent basis. Precautions should be taken to prevent risks from upwardly lifting hinged guards falling under gravity.