Hydraulic Ram Lift - How Big?

[nwav8tor]

I hear all that you're saying and believe me I am NOT convinced yet that the existing beams will hold the load. The beams are already part of the garage's structure and look to be commercially made since the lines between each of the eleven 2x6s are compressed so well that they're hard to see. The final dimensions of each beam is 6"Wx16.5"Hx20'L. As to the type of wood, I just don't know. I'll have to check and see if I can find any markings, but at least it doesn't look to be pine. The spot I'm thinking of making the lift from is 6' in from the end of the beam, so it's not right at the 10' center which should afford a bit more strength than if I was lifting right at the span's midpoint. In addition to bracing the sides of the beam to add stiffness, I might also add some temporary 4x4 posts about 3' on either side of the hoist to take some of the load.

Maybe I better find the guy/company who designed the house & garage 15 years ago and see what the design load was and whether or nor it'll take the additional stress. Failing that, I might just have to find another wood beam/truss products specialist and get his or her input...

[MaineVette]

Dang, I just wrote a really long post and lost it somehow... Oh well...

Basically I said I doubt anyone here will be able to tell you whether your beam will be safe. Perhaps posting a few photos will help us get a better idea of what your facing though.

Generally speaking, timber beams are often deflection controlled and not strength controlled. What this means is that beam sizes are often controlled based on a desire to limit deflection and movement of the beam, and not based on the required strength of the beam. Although it may seem odd, strength and flexibilty are two very different design criteria to an engineer. What this means is that one possible way to determine whether your beam will be ok would be by monitoring the deflection in the beam as you loaded it. Deflections in the range of L/360 (where L is span length in inches) should be of little concern. Deflections of L/240, and possibly L/180 could be ok too.

At a minimum, I recommend installing a punch between the floor and the bottom of the beam on either side of your car. These punches should be solid timbers (like 4x4's) and should be a tight fit and perfectly plumb in the final condition. These punches would reduce the span length and would improve the load carrying capacity of your beam.

Good luck with whatever you decided. And like I said, a few photos might be helpful.

Good luck!

[nwav8tor]

I did some more measuring and research and took some photos of the garage beam structure - The beams ARE glulams!! The upper beam is 5-1/8"w X 17-12"h X 23' total length (20' between supports and 3' cantalever) while the lower beam is 5-18" X 16-12" X 20' between supports (total length is hidden/unknown).

I've found information for newer versions of these type of beams, but since mine are over 15 years old, I'm not sure the data is completely applicable to my particular products. I'm trying to get the exact specifications for my beams from the product manufacturing member association. With a deflection limit of span/360, today's similar products have an uniform load beam capacity of 5100-5900 w, plf (shear controlled) for an 8' span reducing to 800-1000 w, plf (deflection controlled) for a 20' span. I assume w, plf is weight, per linear foot - can any one confirm this and if so, would it be a value in pounds? I've also found lots of other specs, but I can't figure out if/how they apply to my situation. Now all I need to do is figure out how these uniform loads can be adapted to my situation of applying a point load at a specific point in the span.

Here's a pic of the upper beam showing the chain used to hold the chain hoist (note that the upper beam cantalevers 36" beyond the lower beam support and the chain hoist is mounted 10" out on this cantelever. Due to the cantalever and upper wall structure forcing a narrow working width if I was to use verticle support posts, I probably won't use the posts here and will only lift lighter loads that need higher clearances from this position.


A close-up showing the top of the lower beam supporting the upper beam. Also, on the right of the rafter are two more holes where I can move the hoist chain to get it further out into the middle of the garage using the lower beam. I will use 4x4 posts to support the lower beam about 3-4' on either side of the hoist when I use this position. A draw back of this position is the hoist will be 17" lower than the "upper" position which won't allow as much vertical lifting capability.


Here's the hoist mounted from the upper beam. If it was in the lower beam mounting position, it's be about 24" to the right and about 17" lower suspended below the lower garage beam you can see right behind the hoist.


Hopefully I'll hear back from the APA as to the specifics for my older beams.

Paul

[MaineVette]

w is a variable representing the uniform load on the beam, usually in pounds per linear foot (plf).

Going from a maximum allowable uniform load to a maximum allowable point load is a fairly trivial engineering excercise and I'll try to remember to post tomorrow during lunch at work. My manuals are there and I don't want to get the numbers wrong.

So the framing is in a T configuration? It appears you have one beam (lower beam) running between the front and back wall of the garage, and another beam (top beam) running from the exterior wall of the house and extending 3' beyond the lower beam? Is this correct? Does the top beam cross the lower beam at midspan of the lower beam?

[nwav8tor]

w is a variable representing the uniform load on the beam, usually in pounds per linear foot (plf).

Going from a maximum allowable uniform load to a maximum allowable point load is a fairly trivial engineering excercise and I'll try to remember to post tomorrow during lunch at work. My manuals are there and I don't want to get the numbers wrong.

So the framing is in a T configuration? It appears you have one beam (lower beam) running between the front and back wall of the garage, and another beam (top beam) running from the exterior wall of the house and extending 3' beyond the lower beam? Is this correct? Does the top beam cross the lower beam at midspan of the lower beam?

Tim,

That is all correct, except that the upper beam does not cross the lower beam at the exact mid-span of the lower beam. It crosses the lower beam about 4 feet from the back garage wall (so about 1/5 of the total lower beam span. This is just a guess right now because I'm out of town and can't measure it exactly...

Thanks for your help!

[MaineVette]

Tim,

That is all correct, except that the upper beam does not cross the lower beam at the exact mid-span of the lower beam. It crosses the lower beam about 4 feet from the back garage wall (so about 1/5 of the total lower beam span. This is just a guess right now because I'm out of town and can't measure it exactly...

Thanks for your help!

Based on what I've read I have little concern regarding this setup. I understand the chain fall is strapped around the cantilever of the top beam such that the chain is wrapped around the beam only a foot or so away from where the top beam crosses the lower beam. In that configuration that upper beam will have more than enough capacity to carry a thousand pounds or so.

It also sounds like your lower beam was designed to be about 16 feet long and that the load from the top beam is only about 4 feet from the nearest support. Assuming you can put a punch in to cut the overall span length of the beam from about 16 feet to 8 feet that beam shouldn't be an issue either. The shorter you can make that span, the better.

As noted previously I suggest monitoring the beams for deflection and performance as you start hoisting the engine. Take measurements from the floor to the underside of them beam at the midpoint between supports. The total deflection should be less than the span length measured in inches divided by 360 (for an 8' span deflections would need to be less than about a quarter inch). As long as your within this range you should have no issues. As with any lift, make sure you stay clear of the load. Because wood is susceptible to creep if exposed to long duration loadings (lasting weeks or months) I suggest minimizing the length of time the beams will need to carry the load.

Good luck, and keep us posted on how you make out.

Tim

[nwav8tor]

Tim,

Thanks for the input!

I only plan to use the upper beam position for lighter loads that need a higher lift. For heavier loads, I plan to use TWO 4x4 posts under the lower beam to reduce the unsupported span to eight feet or less. I also plan to cut out the sheetrock that is currently on the bottom of the lower beam and mount a flat 2x6 in its place so I don't have to worry about the compressibility of the sheetrock under the lower beam when I add the two support posts.


Paul

[MaineVette]

Tim,

Thanks for the input!

I only plan to use the upper beam position for lighter loads that need a higher lift. For heavier loads, I plan to use TWO 4x4 posts under the lower beam to reduce the unsupported span to eight feet or less. I also plan to cut out the sheetrock that is currently on the bottom of the lower beam and mount a flat 2x6 in its place so I don't have to worry about the compressibility of the sheetrock under the lower beam when I add the two support posts.


Paul

Sounds like that should do the trick. I'd still monitor deflections, but I doubt you'll have an issue.

[nwav8tor]

Tim,

I will monitor the deflection when I'm doing a heavy lift. I'd rather go out and buy an engine lift than have to repair the garage roof structure!!!