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Recent content by bradleyelwood

  1. bradleyelwood

    Air suspension vs leaf suspension and axle torque loading

    I built quite a few trailer axle suspensions when I was a young engineer. The types of suspension/axle system I am referring to is 20,000 pound axles, in single, tandem or tri axle configuration. Air ride suspensions typically provide a low natural frequency vertically. SOME air suspensions...
  2. bradleyelwood

    Kingpin Torque

    Charlynn has systems for steering and some good information on the forces involved. When all the wheels are symmetrically placed about the front axle, and the braking forces are equal right to left, the braking force causes a moment about the king pin causing a compression or tension in the...
  3. bradleyelwood

    Rigid coupling design - friction of bolted shaft flanges

    hello crazyj... Pay attention to Tmoose's methodology, he has it right. On another note, from a design standpoint, what is the nature of the torque? Is it unidirectional, and caused by some sort of gravity load, or is it reversing, going negative to positive? It makes a huge difference as to...
  4. bradleyelwood

    Wheel Design

    Capri, To put my example in perspective, the first tire separated at the bead bundle, and the resulting fire compromised the second wheel which separated the flange from the rim base. When this happened, the wheel separated from the hub, breaking all of the bolts. Then the wheel went out thru...
  5. bradleyelwood

    What are your structural engineering tips and rules of thumb?

    Toad, You are right that rolled shapes are listed in manuals. In my work, I often have to invent other sections which are not in any manual. The rule of thumb for sections is a sanity check for calculated values of unusual shapes. Here is another rule of thumb: the buckling capacity of a...
  6. bradleyelwood

    Wheel Design

    Make sure that your life insurance is paid up and that your beneficiary is someone you like before inflating the tire. Overinflating a truck tire (or car tire) is like playing Russian Roulette. I investigated an accident where first one, then the second tire blew, causing catastropic...
  7. bradleyelwood

    What are your structural engineering tips and rules of thumb?

    the section modulus of a wide flange beam is beam weight in pounds per foot times the overall depth divided by 10. (depth is in inches and section modulus is inches cubed.) the section modulus of a channel or a square tube is beam weight in pounds per foot times depth, (inches) divided by 12...
  8. bradleyelwood

    Load Testing Devices

    The usual approach is to attach electrical resistance strain gages to the steel where the load is being measured. It would be helpful to know the physical size of the 3/4" X 5" band, ie, the length and how its loaded. What are the sizes of the H.S.S. and what length is available for gaging...
  9. bradleyelwood

    Linkage Torque/calculation

    gmc, Thanks for the clarification about how you intend to use the mechanism for slewing rather than lifting.... You can use the virtual work method to equate cylinder displacement times force to torque times angle. Use angles in radians, then be sure your units are consistant for work. By...
  10. bradleyelwood

    Linkage Torque/calculation

    Here is suggestion for a much simpler way to determine whether the mechanism will do what you want. It's called the method of virtual work. In your drawing, attach the object and arm in place of the backhoe bucket. Then move the cylinder a SMALL amount, say 10 mm. Find the amount the center...
  11. bradleyelwood

    A325 bolts in lieu of A394

    90 per cent of the power transmission towers in the US use 5/8 bolts. About 8 percent use 3/4". A few towers use 7/8" bolts. A few tubular poles use sloppy connections with oversize holes, such as 1 1/2" studs in 1 3/4" holes where the fastener does not really clamp the pieces together...
  12. bradleyelwood

    A325 bolts in lieu of A394

    I have built a lot of power transmission towers over the years. For the rest of the engineers reading this, most power transmission towers are tested to failure. It is very interesting to watch a big tower react to simulated wind and ice loading in a full scale test facility, even more...
  13. bradleyelwood

    Hand operated vacuum pump

    I think someone is "pulling your leg"...the handle will allow the shaft to turn less than one revolution. Speaking of "turning a pump backward". When I was in high school, I needed a "hand opeated vacuum pump". I took a tire pump, turned the packing upside down and it worked great. I dont...
  14. bradleyelwood

    Max grade for heavy load on aggregate surface

    19 percent is about the steepest logging road I have ever seen and if you actually drive it or walk it you will swear it is a lot more than that. I would suggest you talk to the trucking company and get a crawler tractor for assist, even if you change the grade.
  15. bradleyelwood

    Computing Section Properties from AutoCAD

    dozer, thanks for the info.
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