Abstract:
At present, nearly 500,000 lorries, trucks and buses are registered in Sri Lanka.
Trucks are widely used for transportation of goods around Sri Lanka. The tires
in these vehicles must be removed during a service, repair or for a tire
replacement. High loads and awkward postures from manually lifting,
lowering, and handling of tires in many instances are linked to
Musculoskeletal Disorders in humans. This research project aims at
developing a suitable mechanism to minimize the human effort and to
overcome the awkward postures and time consumed when changing truck
tires. A survey conducted showed that, 86% had difficulties in mounting the
tire onto the wheel studs and 76% had difficulties in loosening lug nuts. Also,
60% experienced lower back pain due to the tire changing process. Levering,
lug wrenches, impact guns and torque multipliers are the current methods
used, to change truck tires. It was found that, 60% of the employees faced
problems when using the current methods to change tires in heavy vehicles.
The required torque for loosening and tightening of lug nuts was estimated at
600Nm to 800Nm respectively. The worm gearbox strength calculations of the
proposed design were carried using a torque of 1000Nm. Total weight of a
semi-truck tire was taken as 600N and the tire lifting equipment calculations
were performed to withstand a load of 1000N using a factor of safety of three.
Finally, the design was simulated and validated through ANSYS modeling
software using properties of mild steel as for the strength calculations.
