Angle of support and strength capability

AI Thread Summary
The discussion centers on the structural integrity of weight benches, particularly the surprising use of smaller gauge steel in the main support of the backrest despite it bearing significant stress. Users note that as benches become more expensive, the overall steel quality improves, yet the critical backrest support often remains inadequately sized. Concerns are raised about the safety and reliability of these designs, especially when considering the weight ratings of up to 600lbs. Comparisons are made to older models, which seem to have withstood similar loads with thinner materials. The conversation invites engineering insights on whether current designs are over-engineered or if there are valid reasons for the observed choices in steel gauge.
Monkey
Messages
9
Reaction score
0
I have been looking at new weight benches recently. Whilst I can appreciate this is not a weights training forum I think the mechanical loads and the equipment designs can best be discussed here, I´d like an engineers professional input.

Something that's rather obvious is that as benches get more expensive the box section steel they are fabricated out of gets larger and thicker gauge. Something that isn't so obvious is that the main support of the backrest often stays in a smaller gauge steel - I can't quite work this out in my mind, that the main weight support of the bench is in such small section steel, compared to say the legs or other main supports.

I´ve given a few examples of benches and annotated at the point in question, it seems to me this is the part which takes most stress yet it is the smallest gauge steel, even in the flat position where it will actually be taking more stress than in the incline position! In this case that one part of steel is taking a full stress if a lifter is led down on his back with it in the flat position, this bench is rated to 600lbs, that seems a lot of weight for that one 40 x 20mm part to take.

In the flat position the part even takes more stress than in the incline position - I have to wonder why they don't make this part out of larger section steel - It´s something they hardly ever do, after looking at scores of different benches most have a small section steel support there.

Purely out of interest the thoughts are, look forward to any feedback possible.
 

Attachments

  • incline.jpg
    incline.jpg
    31.2 KB · Views: 425
  • flat.jpg
    flat.jpg
    31.2 KB · Views: 447
Engineering news on Phys.org
Maybe it is just total overkill on these new benches. Look at this old school bench from the 60s/70s when Arnold Schwarzenegger was lifting, and not many people will be lifting weight as heavy as these benches took.

Amazing how thin the tube is compared to the current models on post #1
old school.jpg
 
Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'
Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
Back
Top