Wheelwright machines – Rubber tire mounting and/or demounting apparatus – For collapsing or shifting tire axially
Patent
1989-09-14
1991-01-22
Meislin, D. S.
Wheelwright machines
Rubber tire mounting and/or demounting apparatus
For collapsing or shifting tire axially
157 128, 157 16, B60C 2507
Patent
active
049863282
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for mounting and unmounting a tire on a rim, having a device for firmly holding the rim, a motor for rotating the rim, a device for pulling the bead edges of the tire over the wheel flange, and a device for forcing the bead edges of the tire into the rim bed.
2. The Prior Art
A tire mounting apparatus is known in which a rim is firmly gripped with clamping claws on the table of a clamping fixture. The rim is rotated via an electric motor, which is provided with a transmission, so that a tire mounting tool introduced between the wheel flange and the bead of the tire pulls the tire off the rim or pulls it onto the rim, as applicable. The bed of the rim is used for this process. Three or four self-centering clamping claws of the clamping fixture lock the rim from the inside on the rim key, or from the outside on the wheel flange. The clamping fixture must assure that the rim is centered exactly so that the tire mounting tool always remains spaced apart from the wheel flange during the rotation of the rim. The clamping claws are controlled via pneumatic cylinders.
The first step in removing a tire is to force the beads of the tire into the bed of the rim, from their seat on the wheel flange, by means of a forcing tool. As a rule this tool is mounted on the side of the apparatus and is actuated via a pneumatic piston/cylinder unit. To force a tire off a rim, the forcing tool must be used at several points on both sides of the tire, and after being forced off on one side the tire has to be turned over. The forcing tool in the known apparatus requires considerable force, which is exerted on the side of the tire and is difficult to control.
Damage to the tire and rim cannot be precluded in that case. Especially with wide tires, it can often happen that in the process of forcing the tire off the rim the forcing tool can be forced into the bed of the rim, and can damage the rim bed.
The known tire mounting apparatus requires a great number for providing units of force, such as an electric motor and pneumatic piston/cylinder units. Also, a transmission between the electric motor and the rotating plate of the clamping fixture is indispensable. Furthermore, the known apparatus is complicated to use and is not always problem-free.
SUMMARY OF THE INVENTION
It is the object of the invention to devise a reliable, sturdy tire mounting apparatus that is easy to use, which needs only a single energy source, and which does not require complicated transmission mechanisms.
According to the invention, this object is attained in that the device for rotating the rim is a pneumatic motor having a rotor and stator with radially arranged piston/cylinder units and cams disposed on a circle; that the device for firmly holding the rim comprises self-centering arms that are pivotable via the pneumatic motor; that the device for forcing the bead edges of the tire into the rim bed comprises rollers acting simultaneously on both beads; and that the device for pulling the bead edges of the tire over a wheel flange has an element for bracing against the wheel flange.
In the apparatus according to the invention, an electric motor provided with a transmission is not used; instead, the rotation of the clamped rim is effected via a pneumatic motor, which is classified as a low-speed motor with high torque and is operated with compressed air. Unlike an electric motor provided with a transmission, such a pneumatic motor can bring high torque to bear at low rpm without limitation. This advantage is particularly important if a maximum torque must be developed beginning at the stationary device for firmly holding the rim, which with conventional electric motors always entails the risk of locking. The motor according to the invention is economical to manufacture, by comparison with an electric motor having a complicated transmission.
The pneumatic motor-driven self-centering apparatus for firmly holding or chucking a rim has a number of arms, in particular fo
REFERENCES:
patent: 3815653 (1974-06-01), Scott et al.
patent: 4694875 (1987-09-01), Goebel
Meislin D. S.
Stahlgruber Otto Gruber GmbH & Co.
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