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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Rapide Chain Problem
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<blockquote data-quote="timetraveller" data-source="post: 156651" data-attributes="member: 456"><p>It might be worth going back over the history of the ESA. It was clear within few years that the original had problems and this lead to the redesign for the Series ‘D’s. More springs and a better locking mechanism but no change in basic design. Then came the Australian one which had even more springs. Experience by Dick Sherwin on his sidecar outfit showed that even with the addition of a heavy Russian sidecar there was not much movement of this ESA and it paid to remove some of the springs. All these ESAs have a similar design in that the ESA cam design is such that compression of the springs versus rotation is more or less linear and if one uses normal coil springs, which have a linear force to compression ratio, then one is applying a linear resistance. The design advocated by Vic (Oexing) has a different cam design in that the movement between compression of the spring and the rotation of the ESA is not linear. In fact the resistance to compression rises much more rapidly than linear.</p><p></p><p>Then we have Stu Spalding’s contribution of bothering to get springs made wherein one spring gave the same, or similar. characteristics to the pairs of springs used in the original ESAs and clutch shoe centralising I have no idea why it was thought that two springs could be used when one could have the same characteristics. Perhaps post war availability was a problem. Even acknowledging the Spares Company’s wish to produce parts to the original specification I still do not understand why they continue to provide spring pairs but I am prepared to believe that there is something here that I do not understand.</p><p></p><p>Now to the failure of primary chains and dynamo drives. About eighty of the Walkernators are out there, generally being used by the long distance riders who value output and reliability over originality. So far as I am aware there has never been a failure of either the chain or dynamo sprocket when the Walkernator is being used. The only failure at all that I am aware of is that on some of the early ones it was possible for the bearing at the driven end of the dynamo replacement to start to turn on the shaft and in its housing. A redesign by father and son, John and Peter Appleton solved this problem by trapping a steel tube between the two bearing inners, thus forcing them to rotate together. All Walkernators now have that built in. During the development of the Walkernator, by Dick Sherwin and myself, I did originally design the drive with the same multi vee belt as is use in all of them but with the driven sprocket plain, that is no grooves, to reduce the need for alignment of the two pulleys. Such a system is used on some Flymo grass cutters. It did not work in that enough power is being taken by the alternator that the belt slipped on the driven pulley, even when the belt was overtightened. I mention this to emphasise that even with a modern alternator design there is still sufficient power being taken to potentially cause problems with the original design of chain and sprocket and yet none has ever manifested itself. I put this down to two things. One is the inherent shock absorbing nature of the multi vee drive belt. The second reason is the fact that modern alternators do not produce maximum power at all times. Instead the magnetic field is controlled by the field windings which themselves have their electric feed current controlled by the alternator controller. The originally used Iskra alternators could produce 30 amps, the more recent Nippon Denso items can produce 40 amps. At 14 volts that is 420 or 560 watts of power, call it half a kilowatt which is near enough half a horsepower. So the mechanics of the system can take plenty of power.</p></blockquote><p></p>
[QUOTE="timetraveller, post: 156651, member: 456"] It might be worth going back over the history of the ESA. It was clear within few years that the original had problems and this lead to the redesign for the Series ‘D’s. More springs and a better locking mechanism but no change in basic design. Then came the Australian one which had even more springs. Experience by Dick Sherwin on his sidecar outfit showed that even with the addition of a heavy Russian sidecar there was not much movement of this ESA and it paid to remove some of the springs. All these ESAs have a similar design in that the ESA cam design is such that compression of the springs versus rotation is more or less linear and if one uses normal coil springs, which have a linear force to compression ratio, then one is applying a linear resistance. The design advocated by Vic (Oexing) has a different cam design in that the movement between compression of the spring and the rotation of the ESA is not linear. In fact the resistance to compression rises much more rapidly than linear. Then we have Stu Spalding’s contribution of bothering to get springs made wherein one spring gave the same, or similar. characteristics to the pairs of springs used in the original ESAs and clutch shoe centralising I have no idea why it was thought that two springs could be used when one could have the same characteristics. Perhaps post war availability was a problem. Even acknowledging the Spares Company’s wish to produce parts to the original specification I still do not understand why they continue to provide spring pairs but I am prepared to believe that there is something here that I do not understand. Now to the failure of primary chains and dynamo drives. About eighty of the Walkernators are out there, generally being used by the long distance riders who value output and reliability over originality. So far as I am aware there has never been a failure of either the chain or dynamo sprocket when the Walkernator is being used. The only failure at all that I am aware of is that on some of the early ones it was possible for the bearing at the driven end of the dynamo replacement to start to turn on the shaft and in its housing. A redesign by father and son, John and Peter Appleton solved this problem by trapping a steel tube between the two bearing inners, thus forcing them to rotate together. All Walkernators now have that built in. During the development of the Walkernator, by Dick Sherwin and myself, I did originally design the drive with the same multi vee belt as is use in all of them but with the driven sprocket plain, that is no grooves, to reduce the need for alignment of the two pulleys. Such a system is used on some Flymo grass cutters. It did not work in that enough power is being taken by the alternator that the belt slipped on the driven pulley, even when the belt was overtightened. I mention this to emphasise that even with a modern alternator design there is still sufficient power being taken to potentially cause problems with the original design of chain and sprocket and yet none has ever manifested itself. I put this down to two things. One is the inherent shock absorbing nature of the multi vee drive belt. The second reason is the fact that modern alternators do not produce maximum power at all times. Instead the magnetic field is controlled by the field windings which themselves have their electric feed current controlled by the alternator controller. The originally used Iskra alternators could produce 30 amps, the more recent Nippon Denso items can produce 40 amps. At 14 volts that is 420 or 560 watts of power, call it half a kilowatt which is near enough half a horsepower. So the mechanics of the system can take plenty of power. [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Rapide Chain Problem
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