Originally Posted by M McGraw
I “borrowed” this idea
. The second picture is a slight modification I needed to eliminate binding while returning the tail to the floor.
There is more going on with these simple lifts in regard to engineering than might be at first apparent. My engineering background is limited to the shadetree variety but some simple analysis might reveal why some wood lifts slide effortlessly and others may bind.
If binding occurs on the aft slide block then more than likely the cable attachment needs to be closer to the tailwheel centerline. This will decrease the length of the arm supporting weight and the resulting load on the aft block.
Compare the cable attachment geometry on these two lifts:
Mine (cable aligned more or less even with rear of tailwheel, and the cable parallel with the ramp):
Marvin's (lift strap aligned with a point several inches aft of the tailwheel):
The dolly slides up and down with no binding on my lift and I suspect it is because the cable is closer to the tailwheel. If Marvin moves the attachment of the strap closer to the tailwheel (shorten the load arm and transfer weight from the rear slide block) I bet it will operate more smoothly.
I realize this stuff is pretty insignificant in the grand scheme of things but it is still interesting to play with. As a side note--I'm always amazed at how huge structures in antiquity were constructed with highly engineered simple machines.....them folks were smart