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  • MRE Last Word

    THE LAST WORD
    Thank you for all the nice feedback we have received for our "Last Word" ramblings about gears and tyres. It is nice to know that we have been able to help at least a few people have a clearer understanding of what makes a slot car work.
    This week, a few words about motor orientation and the reasons behind it. There are three ways that a motor is aligned in a chassis : Inline, Sidewinder, and Anglewinder. There is a reason for each one, so lets find out why. In all cases we will be referring to 1/32 scale cars.
    INLINE MOTORS. This is when the motor lies along the length of the chassis, with the motor shaft at right-angles to the back axle. The drive is through a pinion and crownwheel (refer back 2 weeks to the "Gears" ramble). In early slot racing days, motors from mainly model trains were used, long open-frame motors that would only fit into the narrow cars of the time by placing them centrally in the chassis. As can-type motors came into use there was basically no change in the chassis layout, and the cars were still quite narrow. Formula 1 cars, even these days, have inline motors because that is the only way you can fit a motor inside the bodyshells. All good so far - except when you get to powerful motors with a big torque effect : when the motor turns, the equal and opposite reaction is to try and turn the chassis in the opposite direction (basic physics). This can be upsetting in a slot car - when you apply pow er the motor will try and lift one side of the chassis, making the car perform differently in right and left hand bends.
    SIDEWINDER MOTORS. The shorter can motors that came along in the 1960s were a bonus for extra performance. The more technical racers soon realised that the reverse torque effect could be put to good use : by placing the motor across the chassis, the front of the chassis would be forced downwards when power was applied, therefore forcing the guide harder into the slot and not upsetting the sideways balance of the car. Essentialy, this should be the perfect design for stability - but it does have one drawback : for many cars the size of the motor and the distance of the motor shaft from the rear axle means that quite large gears must be used, and therefor wheels & tyres must be larger than the spur gear. There is a solution though............
    ANGLEWINDER MOTORS. Technically this is a compromise, but one that is extremely successful. To use small wheels & tyres, it wasn't long before car developers started installing the motor in the chassis at an angle that brought the motor shaft much closer to the back axle. This meant that smaller gears could be used, therefore smaller wheels & tyres could be fitted, and cars could be more realistic while still having good performance. Theoretically, the reverse torque from the motor should act diagonally or at least at an angle across the car, but in practice the effect is minimal and there is still a lot of force towards the front of che chassis, much like a sidewinder installation.
    PRACTICAL NOTES. In general, the way a motor is installed in a chassis can affect the handling in different ways. Obviously there is the motor torque effects mentioned above, but we can also consider centre of gravity and balance. In all cases it is possible to have the motor at the lowest point of the chassis. With inline motors, this can sometimes mean that the motor shaft will be offset below the height of the axle, and normal crownwheels are not ideal. In a perfect world, specially cut or moulded helical gears would be used so that the gear teeth still form a proper mesh with the pinion. SLOT.IT do make crownwheels for this, with part reference SI-GO*** if you need them. With sidewinder motors it doesn't matter how different in height the motor and axle are, the gears will always mesh perfectly as spur gear teeth are straight-cut in relation to the axle. In practice, the same applies to anglewin der motors as the angle-cut gear teeth will mesh at different offsets.
    We can also consider detail and aesthetics in a slot car - if you want to have a full interior and a complete driver you can't really consider an inline configuration, the motor takes up the space where the cockpit and seats would be, so a flat platform and a driver with head, shoulders, and arms is the best you can expect.

    You will probably look at your cars a bit differently now, and assess the dynamic effects of how they are designed. Try a few tests - drive a car with an inline chassis to the limit around bends in both directions and see how it handles. Then try the same with a sidewinder chassis, and find out how much more stable it is through the corners. You will soon find out that powering a sidewinder car through a corner is much more effective than coasting through as the guide will be forced into the slot as soon as you apply power, as opposed to an inline car which will tend to lift one side of the car and reduce stability.
    Of course most of these comments apply to cars without magnets, but if you are using cars with magnets you are probably using poorly designed chassis that need them to make the car driveable in the first place...........

    Scott.....War Eagle River......Tampa, Florida, USA

  • #2
    Ha! "Of course most of these comments apply to cars without magnets, but if you are using cars with magnets you are probably using poorly designed chassis that need them to make the car driveable in the first place..."

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    • chappyman66
      chappyman66 commented
      Editing a comment
      Not always true.....lots of manufacturers now make cars that run just fine on wood or without magnets as long as you change tires. But in the old days.....oh yeah.

  • #3
    And here I thought MRE meant Meal Ready to Eat , lol

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  • #4
    Hey War Eagle , I always think there should be a little bit of laughter in peoples day

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    • #5
      Originally posted by Fathead59 View Post
      Hey War Eagle , I always think there should be a little bit of laughter in peoples day
      Got that right!
      Scott.....War Eagle River......Tampa, Florida, USA

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      • #6
        Originally posted by Fathead59 View Post
        And here I thought MRE meant Meal Ready to Eat , lol
        That's how I read it the first time I saw it. Ha.

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