How to Calculate Pressure Exerted by C in a Lever and Fulcrum Configuration?

[john101]

Interesting set of choices.

I've found two 3/4" strips long enough to fit snugly into the tube.

 

[JBA]

I assume you are still going to cut the tubing to allow welding the strips directly to the lifting arms.

 

[john101]

Yes. And if I understand correctly : then weld the tube onto the arms then weld on the strips and the u piece. ?

 

[JBA]

The top ends of the lifting arms and "U" slot plates should be cut 1 1/2" wide and 3" deep to fit closely to the 1 1/2" X 3" crosspiece bar set.

The crossbar tube should be cut to a length such that when one end of the the 1 1/2" plate set is inserted through the lifting arms there will be enough space between the ends of the tube and the inside of the lifting arms to be able to make a solid strong weld of the bar set to the inside face of the lifting arms inside "U" plates before welding the tube end to that assembly.

Finally, since the crosspiece 1 1/2" bar set should be long enough to extend at least 1/4" or more beyond the face of the "U" plate on the outside of each lifting arm, then a full around fillet weld between the exposed end of the plate set, the outside face of the "U" plate and outer edge of the lifting arm top cap should finish the weld.

Basically the crosspiece two plate set should be welded to the lifting arms as though the 2x3 tube did not even exist and then the ends of the tube should be welded around its ends to the exposed bars fillet welds to the lifting arms.

I am not saying that the whole assembly should not be fitted and tacked together before any welding is done. I am just trying to give a clear description of the type of crosspiece welded end connections I am looking for.

The primary strength of the crosspiece is the from the 1 1/2" by 3" two bar assembly, the 2 x 3 tubing is simply a cover piece that will add needed strength to that bar assembly.

If you have any questions just let me know

 

[JBA]

Disregard the the above post; in error, I wrote it as though the crosspiece slots were in the 2" faces of the 2"x 3" lifting arms. See the below for a correct procedure with the crosspiece slots in the 3" reinforced faces of the lifting arms and that the crosspiece bars are 3/4" x 2 5/8" which reduces the slots' depth to 2 5/8" to make the top of the bars flush with the cut top edge of the 2x3 lifting arm tubes.

Note: Before proceeding with any of the below material cutting and fabrication, I recommend addressing the design and attachment of the piston axle connections on the bottom of the lifting arms to insure that the arms and their reinforcing strips are cut to the correct lengths for the overall assembled arms.

The top end slots of the lifting arms with their 3" x 1/4" longitudinal reinforcing straps should be cut 1 1/2" wide and 2 5/8" deep to fit closely to the 1 1/2" X 2 5/8" crosspiece bars.

(from this point on the term "lifting arm" refers to the lifting arm 2x3 tube complete with its attached inside and outside 3" x 1/4" thick reinforcing straps).

The crossbar tube should be cut to a length such that when one end of the the 1 1/2" bar set is inserted through the lifting arms there will be enough space between the each end of the 2x3 tube and the inside face of each lifting arm to allow making a strong weld of the cross bars to the inside face of the lifting arm and its top end 1/4" thick cover plate before welding the tube end to that assembly.

Finally, since the crosspiece bars should be long enough to extend at least 1/4" or more beyond the the outside face of each lifting arm, then a full around fillet weld between the exposed end of the bars, the outside face of the lifting arm and outer edge of the lifting arm top cap plate should finish the crosspiece to lifting arm connection.

Basically the crosspiece bars should be welded to the lifting arms as though the 2x3 crosspiece tube did not even exist and then the ends of that tube should be welded to the exposed bars fillet weld to the lifting arms.

This does not mean that the whole assembly should not be fitted and tacked together before any finish welding is done. I am just trying to give a clear description of the type of crosspiece to lifting arm welded end connections I am looking for.

The primary strength of the crosspiece is the from the 1 1/2" by 3" two bar assembly, the 2 x 3 tubing is simply a cover piece that will add needed strength to that bar assembly.

Let me know your thoughts and/or any questions on all of this.

 

[JBA]

Below is a sketch of how I visualize the crosspiece to lifting arm connections. (See above for details)

 

[john101]

Ok, I think I got the problem I was having now.

The tube is welded to the crosspiece bars only.

No U piece.

I get what you mean re the lifting assembly at the other end.

Rough idea:

Showing 2" edge of tube with 1" thick bar with hole inserted with additions either side, shaft through them and case wall and piston etc.

 

[JBA]

That is a good start but now the challenge is finding a way to get the same strong reinforcement and load transfer connection between the axle plate and the arm that is now at the top end of the arms.

I am turning a number of variations for that connection running through my mind right now. I need to know what range of bars and plate you have or have access to that I can work with, including the width of the 1" bar you have. Once I have that information I will work on coming up with some connection suggestions.

 

[john101]

I have a number of the 1" which are actually 1 3/16 x 2 9/16 x 7 3/4 " that fit very nicely in the 2x3 tube. they are all pre-drilled for the shaft so I need to use them. Then I have 1/4", 3/16" plate.

 

[JBA]

I think I have found a possible solution for connecting the tubing to the axle bar using your available materials, but, I need to know the distance between the inside edges of the two holes in the 7 3/4 long axle bar(s) and the length from the the inside edge of the axle hole to the opposite end of the bar.

 

[john101]

This is a drawing of the bar.

The lower hole is where the axle goes (c).

The upper hole is serrated and gripped on to a serrated torsion bar suspension on the 'rail car' by clamping it on with a bolt through the small hole.

Can you describe in more detail which dimensions you are after?

note. after writing the above I reread your post and I think you mean between the two bars in the two arms. ?

 

[JBA]

Using your above figure as reference, I am asking for the distance from the top edge of the bottom hole to the bottom edge of the top hole; and also, the distance from the top edge of the bottom hole to the top end of the bar.

 

[john101]

the distance from the top edge of the bottom hole to the bottom edge of the top hole is 3 3/16".

the distance from the top edge of the bottom hole to the top end of the bar is 5 1/2".

 

[JBA]

OK, what I am going to suggest requires a fair amount of fabrication so I will make some illustrations to help you to understand it.

 

[JBA]

One more question, What type and size of spacer on the axle between the inside of the lifting arm and the side of the box are you planning on using.

 

[john101]

my idea is to cut the lower part off a couple of bars and use them as the spacers.

 

[JBA]

Are you going to drill them to fit around the shaft or just place them on the inner face of the lifting tube?

 

[john101]

I mean to cut the lower part that is pre-drilled.

 

[JBA]

Ok, I can work with that.

 

[JBA]

Attached is a suggested bottom connection design. The stacked 1/4" & 3/16" strips welded to the outside face of the axle bar are there to bring that to the 1 5/8" thickness required for a close side to side fit inside the 3 x 2 tubing for a strong welding attachment from the tube to the bar. I would have placed the 1/4" plate on one side of the bar and the 3/16' plate on the other but that will affect the inside 1" spacer clearance between the bar and body of the unit. Unfortunately, the top hole in the bar forced me to shorten the weld slot on the bar side without the added spacers.

I have also added reinforcing strips to the outside of the 2" faces of the tubing in the bottom region where there has been material removed for the welding slots in the 3" faces.

I made a composite using part of one of your figures to reduce my drafting time and the time of my response.

Review this layout and let me know what you think and any questions you have.

 

[john101]

Ok, that's a neat setup. I'm sure I understand all of it. I can do that. At the moment I'm finishing off the cross piece and starting preparing the arms. I'll post pics later.

 

[john101]

current: car battery for visual scale.

yet to add strengthening strips.

Cut crosspiece inserts too short to have them protrude beyond outer strips.

Arms not cut to length. Don't want to make mistake again of precutting to find mistake later.

found I've cut the c shaft too short. ie can't add third outer layer. I think I was miscalculating/mismeasuring for the inner strips.

 

[JBA]

Explain exactly what you mean by the "third outer layer".

Be sure to make a good weld connection between the crosspiece and the bottom slot and the reinforcing plates

 

[john101]

I mean this layer pointed to in red. The rod reaches to the red dotted line.

 

[JBA]

OK, I don't see that as any issue for the arm or the end attachment as long as you are still going to use the two inserted spacer plates for welding.

 

[john101]

Yes I will. That's good. Thank you.