Those miner bolters in production have achieved monthly averages of 18-30 metres (60 to 100 feet) per 8-hour operating shift.

Peak advance rates of more than 91m (300ft) in a single shift have been achieved on several occasions.

Joy developed the 14ED25 with a rugged sump frame mechanism allowing simultaneous cut and bolt operations.

The machine has been specifically designed for the Pittsburgh No. 8 seam and other thin-to-medium seam applications 1.8-3m (6-10ft) thick with good roof conditions.

Two newly designed rugged AFX drill feed units with increased thrust are positioned behind the cutterhead and used to simultaneously insert two 1.8m (6ft) bolts while the machine is cutting out for the 1320mm (52in) advance cycle.

Rib drills are also available for simultaneous rib drilling for one or two rib bolts on each side.

The six machines operating in US mines have achieved availability of 90-99% a month.

“The design aim was to achieve up to three times the operating life of standard miner bolters prior to the first major rebuild, and early indications after over 10 months of operations are extremely positive,” Joy said.

To address safety, Joy has designed into the 14ED25 roof canopies and rib protection shields, as well as incorporating good operator working locations which are ergonomically designed to protect the operators.

By offering increased drivage rates and semi-mechanised operations, the number of operators in the working area is reduced.