Sizing a jack and jack stands

[chrisclark]

I recently purchased a tractor and a trailer and want to have an appropriately sized jack and jack stands on hand in case I need to work on them. Actually, the trailer could use a couple of new tires.

Am I correct in assuming that the jack and jack stands need to support roughly half the weight of the object they're lifting?

The tractor with RimGuard and front end loader weighs about 6600 lbs; the trailer weighs about 5250 lbs. Would a 2- to 3-ton jack and stands would allow an adequate safety margin?

Thanks,
Chris

 

[Looking4new]

Not in my mind. 3 tons is only 6,000 lbs. What are you gonna do with the other 600 lbs you are left with? I would go for 10,000 lb stands and jack. Better too much jack and stands than too little.

 

[chrisclark]

Since a jack only lifts half the vehicle, wouldn't the other half of the weight be supported by the ground or jack stands that are already in place?

Do the weight ratings show what the jack can lift or an individual jack stand can support? Or do they assume part of the weight is being held by the ground / other jack stands and therefore show the weight of the vehicle that can be safely lifted / supported?

Thanks,
Chris

 

[Looking4new]

I'm just saying that I would want more jack capability and more stand than I really need. Assuming of course that it is my life that would be under the stands. As far as I am concerned, more is better when it comes to jacks and stands.

 

[bcp]

A quick search shows there is confusion about jack stand ratings being per pair or each. Some are one way, some the other. Try to get that information from your jack stand source.

The weight of a vehicle may not be evenly distributed. A jack on one side or end may be holding more or less than 1/2 the total weight.

I like a safety margin beyond that of the jack rating itself, so I would use at least a 3 ton instead of a 2 ton for a 2 ton load.

Bruce

 

[chrisclark]

Yes, I agree that excess capacity is desirable, both for safety and equipment longevity. A 20k jack / stands would provide an even wider margin than the 10k you mentioned.

I've never shopped for a jack or jack stands before. I suppose I have 3 questions:
- How do I interpret the weight rating on the jack / jack stands in terms of real world capability?
- What fraction of a vehicle's weight should I expect the jack / individual jack stands to carry?
- What is a healthy margin for safety?

I've read that one should never get under something supported by a jack—the object should be on adequate jack stands first. I also assume that a vehicle's weight is not evenly distributed and that, in the process of setting a vehicle on jack stands, the jack and an individual stand will have to carry at least half the vehicle's weight at some point.

I figure the answers to my 3 questions above will validate or refute my assumptions.

Thanks,
Chris

 

[chrisclark]

Thanks!

A quick search shows there is confusion about jack stand ratings being per pair or each. Some are one way, some the other.

You'd think that there would be consistent standards for that sort of thing.

I would use at least a 3 ton instead of a 2 ton for a 2 ton load.

I definitely agree with a generous safety margin. My 14k trailer has a single 10k jack stand built in for when it's not hooked up. Assuming the stand would have to support half the weight of the loaded trailer, that's also approximately a 50% margin.

Thanks,
Chris

 

[RedNeckRacin]

I would think that getting real close to the jack's operating capacity would make it a chore to operate. I think 2 ton would be the minimum but a 5 ton bottle jack would work well with some crib blocks. I would make sure that the jack stands I got were based on the single loading rating and not the double. Who knows what you may be working on later. If you already had a 3 ton floor jack, I'd say worst case scenario you do a corner at a time.

 

[oosik]

I get the feeling that there may be some misunderstanding here. First is the assumption that wherever the jack is placed under a tractor it will only experience 50% of the weight of the tractor. That assumption is not necessarily true and a sudden shift of the tractor could seriously overload the jack and cause failure.

The exact same condition will apply to a jack stand. Besides why would you want to take on the unnecessary risk of where to place a jack so that you do not exceed its rated load.

My tractor as now loaded weighs 9875 pounds. My floor jack and jack stands are six ton rated. I have no concern where I lift or place the jack stands.

Yes, it may be more than ever needed but I do not want something falling on me either.

 

[sixdogs]

I use the three ton jack stands under my 3800 lb tractors and six ton under the 9000 lb tractor. In all cases I add backup extra jacks if I plan to crawl underneath. Don't forget most our jacks came from China and you can never be sure of the quality. Better to have an extra jack underneath and not need it than need it and not have it.