I want to fit a winch to my trailer just in case we break the car when sprinting it next year. How do I know the rating of winch I need. The car is currently around 650 kilos and I'm hoping to have it down to around 600 at the end of the winter. Most of the winches on the Bay seem to be rated at 1200 pounds which by my maths is around 550 kilos. Would that be safe to pull it up the ramps?

200kg would pull it up the ramps easily. I have one with two speeds. One rated at 100kg and the slower on at 200kg. I've never needed to use the 200kg speed yet!!

Thread on this in the past.

I have one like these with a cheap chiness brand on it, not sure if its the same inside but looks idetical on the outside down the controler and wire lenght so probebly.
- It works and will get the car up the ramp, but its not pretty. Good enough for a one off, partiuarly if theres two of you, but not really for regualar or easy use. Only fractionally better than a manual if at all.

If you want to use use it much i would make sure its got fairleads, a remote controler on a long wire, and a bit more grunt.


Daniel

Are we talking powered or windy-handle winch?

Just a manual windy uppy one

i'm sure it can be worked out by some physics and maths (weight of car, friction, angle etc)
but the 550kg will be for lifting off the ground won't it? sure you can push the car on a flat surface on your own, and you can't lift 550kg!

One of the SMALL ATV winches (electric jobs ) would do the job and be cheap enough.

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But...

Is the trailer only for the 7 or will other cars like a Doner be on it. Because then you might need something heavier.......

I fitted one similar to this:-

http://cgi.ebay.co.uk/ELECTRIC-WINCH-12V-VOLT-1700LB-TRAILER-BOAT-CARAVAN-CAR_W0QQitemZ350278019445QQcmdZViewItemQQptZUK_Trailers_Transporters_Parts?h ash=item518e326975

The 550kg is for a vertical lift but you need to take into account the angle of the ramp to establish what force the winch 'sees'.

Assuming a horizontal pull and a static friction of 25 kgs my sums come up with the following for a 550kg car

5° = 73kg
10° = 123kg
15° = 178kg
20° = 238kg
25° = 308kg
30° = 392kg
35° = 495kg
40° = 627kg
45° = 803kg

ET correct typo


[Edited on 2/12/09 by MikeCapon]

Mike, I'm not sure exactly what those figures are telling me

At a ramp angle of 5 degrees the winch only 'sees' 73 kilos but at 45 degrees it 'sees' over 800, is that right, if so how can it 'see' more than is there.
Sorry if I'm being thick

i was a bit cofused by that too actually, as the car weighs 550kg in a straight lift. even that plus friction, surely it should only go as high as 575kg?

I am assuming a horizontal pull. At 45 degrees you are raising the car by 1 metre for every metre of cable pulled so that alone is 550 kgs of force needed.

At the same time the car will actually travel 1.414 metres (the hypotenuse of a 1metre by 1metre right angled triangle) so the force required is increased by 41%.

550 + 41% + 25kg static friction = 800 kg or thereabouts.

It's the same principle as if you have a pulley in the system. A single pulley will half the speed and half the load but you'll only get 500mm of movement for 1 metre of cable pulled. In this case though it's the opposite. Greater distance covered equals greater force.

Think about a 90° ramp angle with a horizontal pull! How hard would you need to pull then?