Abstract
In this paper, an efficient, affordable, and portable manual automobile tyre changing tool was designed. The tool operates on the principle of second-class levers, where the load to be overcome is situated between the fulcrum and the effort point. The mechanical advantage (MA) of the bead breaker arm and pry bar assembly of the tool was determined to be 11.5. The standard tube size of the bead breaker arm that can withstand stress due to bending moment was determined to be a 2” (50mm) diameter Schedule 80 steel tube. Also, the dimensions of the standard hexagonal bolts to be used at the fulcrum and load point of the bead breaker arm are M12 × 1.5 × 75 mm, while the standard size of hexagonal nuts to be used with the bolts is M12 × 1.5 mm with a height of 10mm. Moreover, the mechanical advantage (MA) of the mount/demount arm and pry bar assembly of the tool was determined to be 5.22. Also, by comparing the angles of twist of two sizes of the mount/demount arm when the tool is used in mounting or demounting a tyre on a 16” × 7” wheel rim, the standard size of the mount/demount arm that can withstand stresses due to bending moment and torsional moment was determined to be a 60mm × 60mm × 5mm square tube. The cost of materials needed to fabricate the tyre changer summed up to ₦21,000. Ergo, the design provides an alternative portable and relatively affordable tyre changing tool that can be afforded by tyre technicians across Nigeria, and other developing or underdeveloped countries.
Highlights
A tyre is a torus-shaped rubber covering that surrounds the wheel rim and transfers the load of a vehicle from the axle, through the wheel rim to the ground, thereby providing traction on the surface over which the tyre-rim combination travels
Syt Factor of safety, Yield strength in shear, Ssy Length of bead breaker load arm, l1B Length of bead breaker effort arm, l2B Force applied at effort point of bead breaker arm and pry bar assembly, RC Length of mount/demount arm load arm, l1M Length of mount/demount arm effort arm, l2M Force applied at effort point of mount/demount arm and pry bar assembly, RF Perpendicular distance from the longitudinal axis of the mount/demount arm to RL, L Modulus of Rigidity, G Length of mount/demount arm subjected to torsion, LT
The design of a portable manual automobile tyre changer has been developed in this paper
Summary
As tyres carry out their functions over time, they fail due to wear from friction or damage in the form of blowouts, and the subsequent replacement of these tyres becomes necessary. It is pertinent to state that the tyre changing process can be extremely laborious, thereby making the technician prone to injury and the wheel rim susceptible to damage, if proper tyre changing tools, machines or techniques are not used during the tyre changing process. Commonly available at the tyre service centres of tyre technicians across Nigeria is not portable, barely useful for the bead-breaking operation, and completely inadequate for the tyre mounting and demounting operation. This makes the tyre changing process at these tyre service centres characterised by drudgery and waste of time. From the foregoing, there is the need for more portable, complete and affordable tools or machines that can carry out the tyre changing process efficiently. The design is based on standard tube sizes, making it relatively affordable and easy to fabricate
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