Safeguarding Greenhouse Crop Shredders: The Vine Pulling Tarp Conveyor

The Concern

Recent injuries have raised concern about the safe operation of crop shredding machines. Although these machines have been used in the industry for a number of years, and safety reviews have been conducted, safe working procedures have proven to be be insufficient at safeguarding against injuries. Specifically, a significant number of injuries have been reported that were caused during the loading of the vine pulling tarp conveyor onto the crop shredding machine.

These injuries were serious enough to warrant a alert from the Ministry of Labour in early 2010. Vine Pulling Machines on Farms clearly identifies a problem with the vine pulling component of crop shredding machines. Upon the release of this alert, GS Engineering Consultants Inc. acted immediately. Our staff have studied the vine pulling tarp conveyor problem, and developed a concept for solving it.

Since developing this solution, GSE has sent out advisories to several companies to rework existing crop shredders to eliminate reliance on safe working procedures.

The Solution

GSE has designed a solution to minimize and reduce the risks to a worker operating a crop shredding machine. Our review of several different machines, coupled with discussions with ministry inspectors, has determined that effective guarding of the problematic area of crop shredding machines can be successfully implemented. These images show a before and after shot of a successfully guarded machine. The first image shows a machine with the tarp drive roller unguarded and wide open which exposes the operator(s) to a risk of entanglement. The second image shows the same machine ready to operate with all the guards in place.

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LEFT: Crop shredding machine with unguarded tarp drive roller. RIGHT: Safely guarded crop shredding machine.

For further safety precaution, additional controls must be added beyond the guards. These controls and safety circuits prevent operation of the tarp feed roller while the guards are open.

GSE believes that this solution will increase overall productivity since, in addition to safeguarding the worker, machine down time for set up is reduced.

For further information on crop shredder safeguarding, or for assistance in designing a solution and having it certified, please contact our office at 519-737-9162.

About Crop Shredding Machines

Description of Machine

A crop shredding machine consists of three main components: a vine pulling tarp conveyor, a shredder, and a discharge conveyor. If the machine can be fed from both sides, there is an optional forth component: a deflector conveyor that is used between the vine pulling conveyor and the shredder. The deflector conveyor directs the product from either side of the machine to the shredder.

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A typical crop shredding machine with a vertical deflector belt.

Use of Machine

Crop shredding machines:


  • gather spent vines and growing medium;

  • deliver spent materials to the crop shredder using a tarp conveyor; and

  • grind and shred spent organic material for disposal through composting or use in bio fuel systems.

Operation of Machine


  1. A long tarp, which will hold the spent vines, is unrolled between rows of crops in a greenhouse.

  2. The spent vines and growing medium are gathered and placed on the tarp.

  3. The end of the tarp is secured to a roller which is attached to, and powered by, the crop shredder.

  4. The tarp is wound up, and all the spent material is pulled towards the crop shredding machine and run through the shredder.

  5. The spent vines and growing medium are drawn through the shredding blades; the mulched output is carried by a discharge conveyor to a hopper or other disposal system.

Operators are involved in securing the tarp to the drive roller, loading the roller into the drive unit, guiding the edges of the tarp as it is being rolled up, and removing the rolled tarp from the machine.