EXCAVATION

TOOLS

Sarfraz Excavator

Development responsibility: HARC

Origin of concept

Prodding is slow work in hard ground, baked mud, or softer ground criss-crossed by roots from plants or trees.

A robust, portable, miniature excavator could greatly speed up prodding by ripping or pushing the earth at a location point.

One of the biggest obstacles facing Afghan deminers is the interiors of houses in Kandahar and Herat which contain collapsed rubble, mines and UXO's. (for photographs)

We think these demining jobs can be considerably safer and faster with hand tools to increase the forces which deminers can apply to break up the compacted rubble. This is the main reason for working on the Sarfraz excavator tool. It is more a tool for breaking ground which can then be safely prodded to check for mines.

Why not use power tools like back-hoes for this work? The reason for developing these manual tools is that back-hoes cannot get access inside the houses which need to be cleared. The walls must be left standing as they are the only records of property ownership and re-construction resources are almost non-existent in Afghanistan. Deminers currently work only with a small pick, a bayonet and a shovel.

We plan also to enable hydraulic power packs to be used. Belarus tractors are common in Afghanistan and they have built-in hydraulic pumps. They can be hired for reasonable rates, and could greatly speed up work with these tools.

Recent trials in Islamabad, Pakistan (January 2000)

	Preparing to use excavator in hard ground conditions. The heap in the background is extremely hard normally with stones and compacted clay. However, heavy rain just before this test had softened the material considerably. (click images for enlargements)
	Excavator set-up, ready to work on ground at far left hand end. The nearer end uses a wood and steel reaction plate to distribute the reaction forces (up to 3 tonnes). The ropes are used for remotely operating the jacking mechanism. This prototype uses a mechanical jack. Future prototypes will use a hydraulic cylinder and hand pump instead. The aim of these tests is to measure the demining work which can be achieved with the help of a tool like this, and compare this with what deminers achieve in comparable conditions.
	Close-up of the front end. A small bucket tool has been fitted. The right hand side is "dangerous".
	Deminer using metal detector to check ground before excavator moves. Any detectable targets are located: the chance of an uncontrolled explosion is significant so direct moves towards a target are to be avoided.
	Deminer working excavator: observers can watch as this is a simulated field test, but in practice the deminer cannot see what the excavator is doing since he needs to take cover. He is approximately 10 metres away. One rope moves the actuator forwards: the others are used for releasing the actuator and retracting the tool.
	Once forward movement has finished, the deminer uses a prodder to work through the loose material and check for mines or other targets. In practice, the excavator would be used for several adjacent strokes (see concept drawings) before this step.
	Alternative "cobra" tool for use in harder ground, penetrating the earth.
	Close up of "cobra" tool.
	Tool kit used for support in excavator use. The long poles form a tripod derrick. One of the tools is used for loose material: this can move material quite quickly, so a hoist mechanism allows the larger bucket to be lifted and emptied out to inspect the material without the deminer having to do the prodding work.

Early Concepts

	Sketch of excavator showing plan view: the excavator can be used for several strokes alonside each other to break up a considerable volume of ground in one operation. The working stroke is about 1 metre.
	Another sketch showing a pictorial view. The idea of using steel stakes (as shown) for absorbing the reaction force failed: the stakes could not withstand more than a 100 kg or so. Remote operation was always assumed but not shown here.
	Sketch of mechanical jacking mechanism which is a modified "Hi-Lift" jack used on 4-wheel drive vehicles. Normal hydraulic lifting jacks are very cheap, but most cannot be used in a horizontal position, nor can they be operated remotely with any convenience.

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All graphics by Demining Research Team. Aug 1998.
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