Published in June 2009 Australian Longwall Magazine

Centennial identified ribs as a risk, with seven people being injured from ribs during the development process over the past few years.

The system is a combination of three innovations consisting of inbye polly rib protectors, third-stage rib bolters and outbye metal rib protectors with hydraulic extensions.

The outbye metal rib protector was developed in consultation with original equipment manufacturer Sandvik and is designed to protect the operator when installing a rib bolt.

The original version of the protector was designed to fit a hydraulic raise/lower cylinder but the team found it did not have the hydraulics to support it, so an adjustable metal bar was fitted instead.

With new rib bolting valve banks installed, Mandalong has been able to fit all its overhauled continuous miners with a hydraulic raise/lower extension and the outer metal rib protectors.

The device is rated at 500kg for the bottom section and 125kg for the top – which has been fitted with decals.

The third-stage rib bolter, also developed in consultation with Sandvik, enables the rib bolter to extend a further 500mm yet still collapse to the original dimensions, enabling single pass drilling.

“This has made rib bolting a lot safer as the head plate could then reach the rib and support it whilst bolting,” Mandalong said in its entry to the NSW Minerals Council OHS Innovation Awards.

The support is a major safety boon for Mandalong, which has recorded rib blowout of up to 1.2m. The innovation also allows for easier bolting up of breakaways and DCB niches.

Mandalong’s third innovation to make up the entire system – the inbye polly rib protectors – was designed to protect the operator while installing the outer roof bolt.

Mandalong designed the protectors with Tomago-based APM Engineering. The device is rated to 750kg for both the top and bottom sections.

Mandalong encountered several challenges in designing the poly inbye rib protector. The drill rig, when tilted out, only just missed the standard metal rib protector so any extension would hit the protector, hence polyurethane was chosen as the material.

The team also had to design the protector to be hard-wearing as operators put the system hard up against the rib. It also needed to be kept in a forward position so it did not get caught when tramming.

The protector’s height was limited as it could not interfere with installing roof mesh and it had to be able to swivel out so operators could still get in from either the platform or from the rib side to perform maintenance and limit any pinch points.

The design also had to allow the drill motor to be tilted out and back.

With all these challenges posed, the team had to come up with a number of solutions and improvements to the original design.

The original polyurethane hinge was replaced with a metal hinge and the rod diameter was enlarged to strengthen the hinge and eliminate damage.

The team put a 45-degree chamfer on the metal hinge’s back edge so rib bolts would not catch when tramming in reverse.

The three mounting holes were counter bored so the bolts would sit inside the metal hinge and the team put a kick in the leading edge instead of just a chamfer to help it run over the rib and stop it catching.

To allow the drill motor to be tilted out Mandalong built a separate independent section at the top hinge.

With the innovation fine-tuned, Mandalong has benefited greatly. The polly rib protector has stopped rib falling onto the drill rigs, virtually eliminating hose damage.

By combining the innovation with hose manifolds designed with Berendsen, Mandalong has experienced an 86% reduction in machine downtime associated with hydraulic hoses.

“We have had several reportable potential

oil injection incidents in the past and many blown hoses costing considerable time and posing a safety risk to personnel,”

Mandalong said.

“Since installing the inbye polly rib protector there has been no reported injuries to operators from ribs during the cutting process.”

Productivity benefits have come from the system’s ability to allow operators to cut and bolt simultaneously.

Mandalong said already other minesites had requested the system on new machines.

Approximate costs for the system are $5600 for the polyurethane rib sprag, $20,000 for the third-stage rib bolter upgrade and $12,000 for the metal outbye rib protector.

The total rib protection system is estimated to cost $A38,000.