reciprocating shaft and pitman arm

[chickenman]

the shaft is mounted to the frame

a bracket with a 3/4" bolt will have to be welded onto the screen frame

the bar chain and bungee are hoocked to the frame to keep the bar running straight, this is important as the bar will cock on the bearings

make sure the assembly holding the shaft is secure and dosnt twist as the shaft rotates

this is paterend after the comercial unit i used as a guide

 

[BHD]

I have seen a flat bearing used instead of a self adjusting bearing in one end of the arm that does not change in arc,

and or centering the bearings in the arm, would probly be beneficial as you would eliminate most side bending and flexing of the Pittman arm,

to use the existing bearing holders weld a "T" to the end of the shaft or Pittman arm and bolt the bearing on the end of the arm, (in line with the arm) some of the arms I have seen use a flat plate, and use the sheet tin bearing holders bolted to one side,

If the bearings are centered my guess is even if it does twist some I doubt if it would be a problem.


but I can not think of any that I have seen that are off set,
some times depending on speed and vibration counterbalancing the shaft may help some,

 

[RonMar]

The bearings should really be in line with the pushrod as BHD suggested. This arm is alternately compressed and extended. If the center of the bearings are not along the center of the pushrod, this will cause flexing of the rod each time the force direction reverses. Depending on the length and weight of material used, this could set up resonance conditions and cause rapid metal fatigue and rod failure(which might get pretty ugly

It will also be easier to make a counter balanced drive eccentric for the engine end if all the forces are as close to in-line as possible. A counter balanced drive will save wear and tear and cut down on engine oil foaming on the prime mover.

 

[chickenman]

the bearings i used were locally available and cheap

the bar did wind up being rather beefy

all said and done i did get that to work reliably

i did think of some of the other suggestions but there were space and cost constraints

 

[Ken]

Look at the old pitman arm and bearings of a PTO driven mower of 40 years ago The sickle bar only needed grease twice a day and seldom failed.

I have considered putting a screen on old mower and using this method of shaking the screen.
just never have the time to get started.
se'ya ken