Mechanism for adjusting the position of the tool carrier arm of an appliance for fitting a tire on the rim of a wheel and for removing a tire from the rim of a wheel
BACKGROUND 
     Appliances are well known for fitting a tire on a wheel and for removing a tire from a wheel, which comprise a horizontal rotatably mounted plate with clamps that can be moved towards the center of the plate in order to clamp the wheel, a vertical pillar on which is provided an arm with an oscillating motion in a horizontal plane above the aforesaid plate and in the aforesaid arm a bar, the level of which is adjustable, having at its lower end a small guiding wheel for separating the bead of the tire over the wheel rim, and also a small pressure wheel for driving the bead of the tire into the groove of the wheel rim, which pressure wheel is located along the circumference of the wheel. 
     In a known appliance there is provided on the vertical pillar a bracket in which is being screwed an adjusting screw with a small handwheel; the free end of said screw presses against the pivoting arm. After the arm has been turned so that the side of the small pressure wheel contacts the wheel rim, the adjusting screw is being turned so that the arm, and thus the small pressure wheel, parts and is set at a small distance from the wheel rim, resulting in the small wheel not being able to rub against the rim and damage it when the plate rotates. 
     This adjusting screw, however, has a drawback in that it is necessary to have the small handwheel make several revolutions before the small pressure wheel reaches the desired position. Thus, adjustment of the small pressure wheel cannot be achieved rapidly. 
     THE INVENTION 
     In order to obviate the aforesaid drawback and thus to obtain an easy and rapid adjustment of the position of the small pressure wheel in relation to the wheel rim, there is provided, according to the main characteristic of the invention, an eccentric rotatably mounted between the pillar and the pivoting arm for pivoting slightly the arm with respect to the pillar. 
     Hereafter will be given a detailed specification of a preferred embodiment of the appliance according to the invention, which specification will be given as an example without any limiting character whatsoever. 
    
    
     THE DRAWINGS 
     This specification refers to the attached drawings, in which 
     FIG. 1 shows a side view of the upper part of an appliance for fitting on tires; 
     FIG. 2 shows a ground plan; 
     FIG. 3 shows a side view on a larger scale with a partial section of the pivoting part of the arm carrying the tools; 
     FIG. 4 shows a section along the line IV--IV in FIG. 3. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     On the bed-plate 1 is mounted a stationary pillar 2, the top of which is covered by a plate 3 with a protruding part 4. On this plate is mounted a shaft 5 around which can be pivoted an arm 6 fixed to a flange 7. Fixed under this arm 6, there is provided a shaft 8 on which is rotatably mounted an eccentric 9. 
     The free end of the shaft 8 is provided with a threaded projection 10 on which are screwed a nut 11 and a lock-nut 12. Between the eccentric 9 and the nut 11 there is furthermore provided a spring washer 13. Due to these components, the pressure on the eccentric 9 is adjustable. Thus the eccentric is rotatably mounted between a shoulder of shaft 8 on one side and the spring washer 13 on the other side. The eccentric 9 incorporates a handle 14 allowing one to force the eccentric 9 to turn around the shaft 8. The excentric 9 cooperates with a cylindric stop 15 fixed on the protruding part 4 of plate 3 by means of a nut 16. In order to ensure the efficiency of this cooperation and prevent any unwanted rotation of the excentric, the cooperating surfaces 9&#39; and 15&#39; of the excentric 9 and the stop 15 are slotted vertically. At the front side the pivoting arm 6 carries in the known way the bar 17, the level of which is adjustable, with a carrier 18, carrying the small guiding wheel 19 to separate the bead of the tire and the small pressure wheel 20 which drives the tire into the groove of wheel A whilst the tire is being fitted on. Wheel A is clamped in the known way between the clamps 21 of a plate 22, which is made to revolve. 
     For fitting on a tire, the tire is placed obliquely above wheel A so that the bead of the tire is already partly located in the groove of the wheel rim. Then the arm 6 is pivoted towards the wheel and the level of the bar 17 is adjusted until the small guiding wheel 19 rests on the wheel and the side of the small pressure wheel 20 contacts the edge of the wheel rim, so that the side of the tire passes under the small pressure wheel 20 and the bead of the tire passes along the circumference of the small guiding wheel 19. If the handle 14 of the eccentric 9 is now being turned in the direction f, the eccentric 9 presses against the stop 15 and moves immediately and without effort the arm 6 over a small distance, resulting in the small pressure wheel 20 being located at a small distance from the wheel rim, so as to avoid any contact with same. When plate 22 with wheel A is made to rotate, the tire is pressed on the wheel rim along the whole of its circumference, any possibility of the rim becoming damaged by the small pressure wheel 20 being excluded. For mounting the other bead of the tire, the procedure is the same. The same advantage is obtained when removing a tire. 
     It is clear that the form and dimensions, and relative arrangement of the components hereabove described may differ without going outside the scope of the invention.