Cycle News - Archive Issues - 1970's

tlusqyama'. Aulomak Looking at the transmission as a whole, it's a prett y complicated device, The only way to understa nd it is to look at each section, realize how it works, a nd then p ut it all together. There are two basic methods of l .. ans mitting power used in the Husky Au tom atic: T he clutches and the oneway bea rin gs. Both are simple yet clever devices. Crankshaft Fig. I Clutches Clutches (fig. I) work ir, a manner simi lar to drum brakes. A set of shoes (three in this case) expand to come in contact with the inner surface of a drum. Look a t the ph oto (fig. I). You can pick out the three brass "shoes" that are pinned on one end to act like a hinge. The other end is free but held in place by those coil springs. When the shoe assembly is spun fast enough, centrifugal force exceeds the strength of the springs, the free ends of the shoes expand outward, and they come in contact with the drum (t ha t narrow band a round the shoe assembly). At that point, depending on which is spinni ng faster at the time, either the shoes will d rive the drum or t he d rum will drive the shoes . It works both ways at different places in th e trans m ission, a point that will become clear la ter. Fig. 2 One-way bearings 10 One-way bearings (fig. 2) are . something completely new. W e've never seen anything like it in any other mechanism. Bas ically, they ' work much like a ratchet -- power is transmitted in one d ir ect ion it freewheels in the ot her direction. T hose funny-shaped " bearings" that are set on an angle are what we're tal king a bou t (look at fig. 2). W he n the outside bea ring 'race is spun in the direction of the a rrow the inside bearing race " locks up" and is driven by the outer on e. When rotating speed of the inner race exceeds that of the outer one, the bearing freewheels , allowing the inner one to spin at the . Fig. 3 ./ II \ 4th 3rd 2nd 1st Output faster rate. There's absolutely no slip page or backlash in the bearings . These one- way bearings are the key to the Automatic's shifting. The outer race would be connected to the lower gear; the inner race would be connected to the higher gear. Depending on the speed of the bike and motor, the transmission automatically selects exactly the right gear. Shifts are made to keep the motor at or near the torque peak at all times. Putting it all together OK, let's sta rt at the beginning. We'll kick the motor over , put it in gear , and run it through an accele ration test to see how the transmission functions . Starting the motor Obviously th ere has to be a device somew here in th e system to disconnect t he tr ansmi ssio n for starting t he mo to rcycle. Otherwise, revving up th e motor to clear it would have the bike wheelying off when the clutches kicked in, leaving a confused rider either standing alone on the trail or flapping from the handlebars like a union suit on a clothesline. There's a ha nd leba r mo unted lever for that purpose. It 's not shown in the photos but here's how it works . When you push it down into the .locked position, the lever does two things. First, it disengages the first (input) gear by sliding it off the spline that normally drives it. Look at the center photo in figure 3, the assembled transmission. First gear (input) is labelled; it's the one on the right end of the front set of gears. There's a coil spring right beside it. That spring is what holds it on the spline. The handlebar lever controls a lever that fits down in between first gear and the one next to it (second gear). When you engage the lever, it simply pushes the gear over toward the spring, off the spline and lets it spin freely on a smooth shaft. The second thi ng the handlebar lever does is a pply a small brass "b ra ke shoe" to the outside of the first gear clutc h drum. Its pu rpose is to stop or slow the d ru m which is started spinning when .t he rider revs the motor to get it ru nning clean. W hen the motor returns to idle, as it must before you can engage the transmission, the first gear clu tch d rum would still be spinning if the "b ra ke shoe" wasn't there to slow it. Early model Automatics didn't have this feature, and riders had to wait longer for the works to stop spin ning before they could take off. Letting the Automatic do its thing There's a warning decal on top of the gas tank which reads as follows: . "IMPO RTANT. Engine MUST be at IDLE before engaging gear drive." If the rider releases the handlebar lever with the motor above idle, he's not giving the first gear clutch drum a chance to stop spinning. The clutch drives the spline that the first gear (input) is supposed to slide on to. The result, of course, is tha t the nonmoving gear is jammed against the spinning spline, a nd inste ad of engaging it only grinds. It's a safety feature. If it did engage, the bike would jump a head u ncon trolla bly. Orice the machine is a t idle, and the ha ndlebar leve r engages t he gear drive, all th at's left for you to do is twist the throttle. As you do, the first gear clut ch (p hoto in top left of fig. 3) reaches a high enough speed to ex pand a nd drive the first gear clutch hub . The hub is rigidly attached to the front primary gear, and it in tum transmits the power to the other primary gear. The second pri mary gear is rigidly a t- (Continued on page JI)

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