Tongue weight

[Walt]

I keep thinking that I could put a pressure guage on a small hydraulic jack and create a device to weigh, for example, a trailer tongue. Since the jack is covered with rust scale, I'll call the device a "scale." Bad joke aside, has it been done?
Walt

[John Newman, Jr.]

You would need to know the diameter of the piston in your jack and be able to drill & tap into the cylinder to install a gauge, then devise a chart or table to coordinate the reading of what the gauge shows to the actual weight.
OR...
What you need is a cylinder and piston with 1 square inch of surface. This works out to 1.1284" diameter. (Area of a circle = radius squared x pi) So the radius of 1.1284 diameter is .5642 X itself =.3183 x 3.1416 = 1.000 (square inch area) fill the cylinder with oil and add a pressure gauge of appropriate range and you have a hydraulic weight scale. A 100 lb weight bearing down on 1 square inch of surface should then read on a gauge as 100 psi. The only limits will be the range of your gauge and the integrity of the seals on the piston.
See hastily drawn sketch below:
Good luck,

[Fred_M]

I built several devices much like that in the past, but my machining abilities being limited I used off the shelf items. I forget the exact year, but many an automotive wheel cylinder was made with an 1 1/8 inch bore. If your parts store still has paper manuals they are easy to find. You mount that in a piece of channel iron with a bolt in the bottom to hold one pistion, and a valve (out of a car head) in a hole in the other to act as the scale table. Grind the ends round to fit the wheel cylinder on both ends. Plug the inverted line fitting on the wheel cylinder with a inverted flare fitting. The bleeder with be straight pipe thread, use it with a fitting to mount a 1000psi gauge (or drill and tap it bigger if you wanted). Lay it on its side and fill it with brake fluid and attach the valve and you are done. Fred

[Michael Studier]

Twenty years ago, while I was working in a boat yard where we built 100 foot long motor yachts, we wanted to know the weight and center of gravity (balance point) of the hull at various stages of the construction.

We got four hydraulic jacks, two large and two smaller, and put the large ones under the keel one near the fron and one near the back. We put one of the smaller under each chine (side angle), and then hooked them all up to a sensitive pressure gauge and a hand hydraulic pump through a manifold.

We calculated the area of each of the pistons, and then pumped fluid into the cylinders one by one until we got the boat about 1/4" up in the air. We read the pressure on each cylinder and then did the muliplication and added them all up to get the total weight of the boat at each stage of the construction.

We were weighing between 35 Tons and 65 Tons this way, and the setup was sensitive enough to register a single workman stepping off of the ascaffold onto the boat, or if he walked from one side to the other.

We thought about getting a powered pump, but we were concerned that someone would get too entusiastic and lift it way up in the air and then if a jack should fail it might tip over. We figured that a 1/4" drop would not hurt anything so we stayed with a manual pump to slow the whole lifting process down.

[Economy Bob]

Why not go this route? http://www.sherline.com/lm.htm

[John Newman, Jr.]

Well, that's a pretty little thing, but it cost 110 American Dollars. Looks a whole lot like the rough sketch I posted - and I swear I did not know about this model before hand. Being the 'King-O-Cheap', if I wasn't already capable of making my own from scratch, I would definately lean towards Fred_M's clever method using a brake cylinder.
Ingeniuity + Salvaged Parts = Interesting & Unique
Go to store + Hand somebody $$$ = Boring & Common

[Paul Spence]

Many years ago I got tired of the bathroom scale and board device. Threw them out when I got my SHERLINE Trailer Tongue Weight Scale. Sure comes in handy in loading/positioning "STUFF" on the trailer. Then I got one of those weight distributing hitches (at the flea market of course). What a difference, never leave home without them .

[John Hammink]

I always use this weight tester, costs just $7.50

[twslandlord]

I bought a Sherline 5000# scale from Tabletop Machine Shop for $106.09 in 2006. It's hydraulic & very compact.

[Jim Tremble]

Originally Posted by Walt

I keep thinking that I could put a pressure guage on a small hydraulic jack and create a device to weigh, for example, a trailer tongue. Since the jack is covered with rust scale, I'll call the device a "scale." Bad joke aside, has it been done?
Walt

Heck, all you have to do is find someone 200 lbs. and stand on the back of your truck. Record the height with a tape measure from the ground to the hitch.

Then find someone about 300 lbs. and do the same thing.

Tongue weight should be between 200-300 lbs.

If you are within the first and second measurements, you will be safe.

John, is this CHEAP ENOUGH ??

Jim

[KeithW]

The spring rate on my Tahoe is about 200 lbs per inch. I've used the tape measure trick many times.

keithw

[Gasengin]

I have heavy mud flaps made from thick industrial belting on my pickup. I left them a 2 to 3 inches off the ground. When I load something heavy, I place it on the trailer so the mud flaps almost touch the ground and everything works out right. As long as the vehicle and trailer are on level ground, you can tell by "eye" where the load should be placed. BTW. The required tongue weight will vary with the weight of the trailer and load. More weight requires more tongue weight to trail correctly.