Tractor backhoe - homemade

[BFreaky]

I will do it with S355. It turned up good last time. Only this time I've reduced the wall and bottom thickness and overall height of box sections. Max height on the first one is 340 mm, on rk 525 it was more then 400 mm. The point is to reduce weight to get more load capacity

 

[BFreaky]

I wanted to ask you which material are you using for the pins. I used 42CrMo4V but there is a problem with it...when you weld pin ends most of welds crack if there is some force... how do you solve that on your machines?

 

[dfkrug]

I wanted to ask you which material are you using for the pins. I used 42CrMo4V but there is a problem with it...when you weld pin ends most of welds crack if there is some force... how do you solve that on your machines?

What is wrong with mild-steel pins and replaceable sleeve bearings?

 

[BFreaky]

Everything . The point is to have hard pins to get as much uptime as possible. Bushings are cheap and can be replaced quickly but pins are not

 

[love4god]

outstanding work,the best fab work i have seen in awhile,congrads,,
godbless

 

[BFreaky]

Thank you love4god. I hope new one will be even better...at least that's the idea

 

[love4god]

your welcome Bfreaky
I will be watching for your new builds,,
Godbless

 

[Renze]

42CrMo4 hardened and ground, is by far the most used material for pins in earth movers. We allways lathe a small recess on the pin so the tab plate is aligned on a 2mm edge, then the rest is lathed to a 45 angle as thick as the tab plate minus aforementioned 2mm, so it can be welded flush.

42CrMo4V has a high carbon equivalent, so it easily gets hardening cracks in the heat affected zone, or HAZ. Mostly tabs are welded with high amps, high heat input so the mass of weld cools slower to the mass of the pin. In case of problems, preheating the pin and tab is the only way to get the same strength as a weld in mild steel.

 

[Renze]

Oh, and breaking tabs and locking bolts means that there is too much friction in the bushing, so that the rotating force on the hinge is transferred to the locking tab...

It usually indicates fretting due to lack of lubricant, or misalignment of the bores, or play on the bores so the locking bolt is loaded whenever the pin wobbles.

 

[Renze]

...to be able to take pins out, years from now, it is also good to lubricate also the static bores in which the pin sits (not just bearing surfaces) with Copaslip (copper grease) or Keralube (ceramic paste) to prevent fitting rust. I remember at the wheel loader factory, guys from the service department running all yelling into the production department, cursing the guys who forgot to put keralube on tight fits, because in 2 years the bores had corroded so tight that they had to torch the pin out of the hole....