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Boom and Blocked Chute Protection – Hawk Microwave Switch

Application problem:

1. The customer had previously used lanyard rope switches, to protect the boom on stacker/reclaimers, from coming in contact with stockpiles. Lanyard rope switches, require high maintenance support, to keep them operational. If the lanyard rope is not tensioned properly, the system will not work. Brackets supporting the lanyard rope were frequently bent by the boom coming into contact with the stockpile.

2. The customer had used tilt switches and RF probes to protect against blocked chute occurring in the conveyor transfer chutes. Build-up in the chute over both probes was a problem. Speed of response was slow for the probes, because “on” delays had to be used to overcome intermittent impact by the product on the probes. The customer wanted a fully fail-safe blocked chute switch that could be pre-tested on each start-up of the conveyor system. Each blocked chute problem was costing the clients thousands of dollars in down time.


1. Hawk Measurement Systems (HAWK) used our long range remote microwave switch, one pair each side of the boom, to replace the lanyard rope switch. The beam angle of the sender was sufficiently wide enough for simple calibration and commissioning, as well as compensating for the boom deflection when under load. The microwave is not affected by dust, has a robust construction and maximum range of >100 metres (328 ft).

2. HAWK used our non-intrusive heavy duty remote microwave switches to replace the intensive tilt switches. Because there was high impact and vibration in the transfer chutes, HAWK used “UHMW” wear plate windows and mounted the microwave sender and microwave receiver remotely. The microwave amplifier was mounted in an area where maintenance personnel could gain access. The heavy duty microwave worked in all conditions, with dry ore, wet ore, fines and bulk material. Build-up inside the chute only marginally reduced the signal strength of the microwave, which has a maximum range of 100 metres (328 ft). The client used the remote pre-test feature to check that the microwave was working, each time the conveyor system started up. Some ceramic windows were used, depending on the application and chute design.

Ordering information:

Boom Protection System:

Blocked Chute System:

For more information on the product used in this application