(Introduction, results, summary) (PDF, 69 kB) - Queensland Mining ...

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Other observations made by the workshop included: 1) Most cracking occurring under lock ring and back taper area. Cracks in the pressure section may not become an issue until the cleats are released. 2) Plastic deformation occurring on rims after certain operating and pressure conditions. 3) Manufacturers are responsive to changes/developments; this needs to continue. 4) There is concern with equipment manufacturers not keeping pace with wheel/rim/tyre improvements, particularly with local improvements. The main concern here is with 63-inch rims. There are currently only three manufacturers, (Rimex,Topy and Titan), with 2 of those supplying around 95% of the market (Rimex and Topy). The forces on this wheel are such that the standard HDT designs are non-performing, even where original equipment manufacturers have dramatically increased the quality of their wheels. 5) Retaining force is reduced for every retorque that is carried out. Wheel spins, studs fatigue. Stud replacement. This is potentially a significant issue. Major improvement in clocking vs. sequential torqueing. See 7.2 below. 6) Stamping of all components. Some sites package all of the components after repair to avoid mismatch. 7) Lock ring tab / retainer hoop “sure lock” found on some rims was designed to tyre inflation if lock ring was crocked. It may inadvertently prevent lock ring from physically coming out of gutter unless tyre is completely deflated and the bead seat band depressed. Needs to be followed up. 8) There are also lock ring locks and clamps, which will increase the integrity and security of the seating of the lock ring. 9) Concern was raised over Tyre Servicemen working alone on night shift. Night shift is usually a period of higher fatigue and Tyre fitting is a critical task containing a high amount of potential energy, not the same as operating a laptop computer. 10) Can be difficultly getting an 830E pos 4 or 5 rim to free up some times. Nowhere to effectively jack rim between chassis and rim base. Most jacking occurs on the back flange. 11) There can be seating problems with Dresser phase 2. 100% pressure often required seating tyre on bead seat. Tyre Fitters Workshop Townsville 2 Sep 2004: Minutes and Report. Author: Peter Power Page 8
7.2 Studs, Torque and Tension RIMEX has provided information in relation to the relationship between torque, friction and tension achieved on wheel studs. The information is included in Appendix 6. In <strong>summary</strong> torquing a wheel nut to a specified tension does not necessarily mean that the desired tension will be achieved in the wheel stud, particularly where dirt, rust and other impediments are involved in increasing the friction resisting torque. In one test, with a new wheel nut and stud, the desired tension was achieved through the first torque but after releasing the nut and retorquing the nut to the same torque the tension was reduced by approximately 15% due to galling on the wheel nut from the first torque. Other points raised include an indication that tapered rims may require more retorques than a knave plated wheel. Sites should closely review their retorquing procedures and determine that the required tension in the wheel stud is being maintained and careful consideration to be given to a stud change-out policy. 8.0 Summary of Recommended Comments to AS4457 Committee These comments will be recommended to the AS4457 committee for review. 1) The maximum pressure of 35kPa for tapered mounted rims is not practical for very large earthmover tyres. There is no one particular pressure that will suffice all situations. There is a variation between mine sites using identical tyre sizes in terms of the pressures identified in Standard Operating Procedures for handling them. Tyres should not be handled with pressure unless the integrity of the components is established. As stated above the large tyres, 40.00R57 and larger, cannot be managed well at 35kpa. The larger 55.80 R63 tyres may need up to 200kPa inflation pressure to be managed by the tyre manipulator. These problems are exacerbated in wet weather. 2) During reinflation of a tyre the airline should also be long enough to allow the tyre servicemen to stand away from any exploding components. There should be a ‘T’ piece in the line, at a remote location, that allows the servicemen to immediately drop the air from the tyre should something go wrong during the inflation. A fusible link in the valve line in the event of a tyre fire adds another level of control. 3) A tyre which has been run flat or in a severely under inflated condition should not be fitted or inflated until the integrity of the tyre and the integrity of the rim components has been established. Participants in the workshop said that if the inflation pressure had dropped to or below a certain pressure during operation then the tyre should be removed for inspection and not Tyre Fitters Workshop Townsville 2 Sep 2004: Minutes and Report. Author: Peter Power Page 9
Page 1 and 2: North Queensland Tyre Fitters Works
Page 3 and 4: 1.0 Introduction A one-day Tyre Fit
Page 5 and 6: 6.1.2 NRM Presentation on Fatal Acc
Page 7: that allows the servicemen to immed
Page 11: iv. How much material can be machin

(Introduction, results, summary) (PDF, 69 kB) - Queensland Mining ...

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