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 The variable speed unit is represented on the diagrammatic drawing on
Fig.1. showing its essential components.
On driving shaft 1 and on driven shaft 2 are mounted the couples of bevel
wheels A,B respectively C,D which,together with alloy steel ring 7 form the drive.Driving takes place between the bevel
surfaces and the toric surfaces abtained on the ring; change of the speed ratio is performed by means of a displacement in
axial direction of wheels B and C, which causes the shifting of the contact points between the ring and the
wheels.
More exactly,while wheels A and D are shrunk on their respective shafts,wheels B and C can slide in axial direction,so that when B
approaches A,C moves away from D by the same extent and vice-versa.
The motion of the wheels is performed simultaneously by
turning, by means of the appropriate hand-wheel, toothed pinion 3
which engages with rack 4, cut on the outer surface of cylidrical sleeve 5.
This sleeve is stiffly connected with sleeve 6 so that against a displacement of the first sleeve(which causes the shifting of
the wheel) corresponds an equal movemen in the same direction of the second sleeve and consequently of wheel C,A
self-adjusting device sees to it that ring 7 constantly exerts the right amount of pressure onto the four gearwheels A,B
and C,D.
Speed ratio is determined by the ratio between the diameter of the
circumferences of driving wheels and the diameter of the circumferences of the driven wheels on which occurs the friction with
the ring.
These diameters depend from the relative position imposed to wheels B and C.
Beacause of the simmetry of system, it is possible to abtain speed ratios
lower or higher as one, viz. The variable speed unit can work both as a speed reducer or as a speed
increaser.
Futhermore, unlike many other variable speed products, the AGOSTINI unit can transmit the drive in either direction of
rotation.
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