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I am designing a block and tackle system to haul wood up a ramp onto my porch. The issue I am having is that the rope seems like it will rub against the top of the ramp and cause it to fray. How can I prevent this from happening?

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JMD
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  • Hey JDM, welcome to engineering.SE! This question however seems more appropriate for diy.SE. – Wasabi Sep 02 '15 at 19:38
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    Agreed with @Wasabi, not really an engineering question. However, adding a pulley at your friction point would take care of your issue, though that would negate the ability to get the load all the way to the flat part. Maybe move the pulley vertically upwards so that you have a clear line of action between the load and the pulley? – grfrazee Sep 02 '15 at 19:43
  • If you look at the applied-mechanics tag there are some other pulley questions so I thought it was appropriate. :) Also if I move the pulley up won't I just make the load tip up when it gets to the top of the ramp? – JMD Sep 02 '15 at 19:45
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    @grfrazee, or use two parallel lines of pulleys placed not along the trolley's axis of translation and then tie the rope not to the front of the trolley (where the rope "pulls" the trolley) but around the back of it (so that it "pushes" the trolley). This would probably allow you to get the trolley onto the horizontal porch. Once on the porch you'd need to untie the trolley and pull it by hand (or via another pulley system). – Wasabi Sep 02 '15 at 19:49
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    Can you just put a smooth metal plate at the drag point? – Chris Mueller Sep 02 '15 at 20:20
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    Pulley at top of slope. | Existing pulley height slightly above rope attach point on cart when cart is on porch and level. | Rope attach point as high up on cart as practical. | Go. – Russell McMahon Sep 03 '15 at 07:21

1 Answers1

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Here is how I would solve this in true bodge-job fashion:

Materials:

  • 2x bricks, the type with holes in
  • 1x short section of broom-handle
  • 1x short plastic pipe, or toilet-roll tube (bigger than broom handle)
  • 2x pencils, or bits of string, or something

Assembly:

  • Put the pipe over the broom handle such that it can rotate freely
  • Support the broom handle in the holes between the two bricks
  • Optionally drill holes through the ends of the broom handle and put a pencil through it, to stop it sliding sideways and dropping out of the holes. Alternatively put a bit of string through it and tie to the brick, or anything really.

Usage:

Place the roller at the apex of the hill. The rope will roll over the roller then lift off as the truck gets to the top. The truck will drive over the top of the roller assembly as you pull it onto the flat section.

Jobsagoodun.

jhabbott
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