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 The first step in building your JYH is to collect the things you think you are going to need. Some will be discarded while you will find you need other items. I purchased two 3 foot lengths of rail road rail and have decided not to use them. I already see things I hadn't thought about previously. However, this is a start. The next step is to measure the parts and do a little reverse engineering. Crank the axle pinion and count the wheel turns and calculate the ratio, measure the pulley diameter. Measure the wheel lug spacing and determine the bolt circle, the universal joint yoke bolting for mounting the pulley, the motor shafts and mounting bolt patterns. Of primary importance to this design is the working length and stroke of the shock absorber. All I did when I bought it was tell the auto parts guy I wanted one that took cross bolts on both ends (real scientific on my part!). The shock turns out to have 8" (20cm) of stroke with some room left over at the ends. This means that we have to limit the crank to 8" (20cm) max. Then if the ram sticks and doesn't move or the clutch is engaged too slow we will not over travel the shock. This happens to be the same as the published stroke for a 25# Little Giant. However, I measured my 50# and 100# hammers and they both have a 6" (15.24cm) crank throw! Obviously they were taking the upward over travel into the spring as stroke. The shock absorber linkage will likely shorten the throw a little so we will design for something in between. I'll post my revised design sketches next! Continued on JYH p.2 |
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