Open Cut » Maintenance & Equipment
The aim of this project was to design, construct, and commission a transportable tyre handling testing rig. The test rig enables the frictional grab force between tyre handler pad and tyre to be quantified for a range of tyre types, tyre tread and sidewall wear modes, and surface wetting conditions.
The resulting rig consists of a base structure, which is weighed down in operation by 6 concrete ballast blocks, each weighing 2t. ;A boom gate, powered by an electric winch, opens to allows the tyre handler to place a tyre in a cradle platform. The platform is supported by 4 load cells, one under each corner, each capable of measurement in compression and tension. A harness, comprised of a number of slings and tie-down chains, is used to secure the tyre to the platform. Once a tyre is secured, the boom gate is lowered and the operator of the tyre handler proceeds to grip the tyre in preparation for a regular lift. The combined assembly of the tyre and platform are lifted, up to around 10 kN vertical force. The operator of the tyre handler then progressively releases the hydraulic pressure in the grip cylinders until the tyre slips. A pressure sensor installed on the valve block of the tyre handler, previously calibrated against a pair of load cells mounted to the rear frame of the test rig, enables the grip force to be monitored and the point of slip and corresponding factor of safety to be determined.
Functional performance testing and initiall tyre slip tests were carried out which included:
- Validation of the transportability of the test frame;
- Verification of the clamp force load cells;
- Validation of the clamp force load cells to determine the tyre handler clamp force gain factor;
- Validation of the platform load cells in compression;
- Validation of the platform load cells in tension;
- Fall back test containment of a tyre within the test frame;
- Restraint test of the tyre harness;
- Validation of the tyre slip testing procedure; and
- Accuracy and repeatability of tyre test measurements.
The results of this project will assist to:
- Establish a rigorous criteria for testing the performance of tyre handling gripper performance;
- Have greater confidence in the safety claims of OEMs manufacturing tyre handling equipment;
- Develop detailed risk management plans for managing tyres across a wide range of operation scenarios and conditions.