I keep breaking pitman arm (see pic)

I got a New Idea model 30B sickle mower a few weeks ago at an auction. I've sent away for the manual but I get impatient and want to use it now. So far I've broken the pitman arm 3 times. I greased everything and it cuts good for a while (just cutting high grass) and then it shears bolts or breaks the arm. Could it be because the cutter bar is dull? I thought it was fairly sharp but with grass maybe it binds up. I'll wait for the manual this time but I'm at a loss. As a kid I sat on one of these for hours and it never seemed to break. Thanks for any ideas.

Are you sure it is not binding up? How are you making your new ones? Was the original pitman arm on the mower when you bought it? If yes, use it as a pattern (drill jig) and make replacements from hardwood.

After installing turn the mower over by hand and listen for any binding or hitting.

Hope this is old news to you and you have already done it.

Bill.

also a tip if not binding is to duck tape up the arm when u get it on.. silly but i learned this from a old farmer who swears by the old ford 501, the tape helps keep vibration down make it last longer

Thanks Bill. There was a tubular steel pitman arm on it that broke at the weld point. I had it welded but checked with a implement dealer and he said it should be wood. I used that steel one as my template. I did buy two wooden ones but I wanted to test things on one that I made. I do have a few oak ones that I will put on next but I want to make sure that I'm not missing something. The one in the picture is pine, I think.

Been about 40-some odd years since I used a pitman arm sickle mower, but..........is the knife in register, i.e., does a knife section center under the guard at each end of the stroke?

If the sickle or gaurds are wore it will pull harder and also green grass is harder to cut.That puts exta pressue on the pitman arm.Dad had one of those,it was common to break the pitman arms.We bought ours from the local TSC farm store.That's probably why they did away with that design.

Just an thought - You are running it no faster then 540 RPM's

Most of us haven't seen anything dry since last August, but dry tall grass is really hard on a sickle bar mower. The mower has to work like a pair of scissors.

Like the other guys said, the sickle sections and the ledger plates (on the guards) have to be sharp, the guides have to hold the sickle in place, and the guards have to hold the ledger plates in place. Make sure the pitman is the right length - one of the guys called it in register.

Something is probably still wrong but pine ain't gonna cut it.

Can you slide the knife easily by hand? Is that bearing near the break freely spinning?

I would almost bet you hit the nail on the head. I have never broken a pitman arm from plugging which happens a bunch in wet down grass in a hay field. The slip clutch should save it from that. The last pitman arm I broke was from rot. Mower sets out year around, I made one quick out of a green treated deck 2"X 4" about five years ago and it is still in good shape. I run about half throttle and still cuts good. Running the throttle up on an old mower like mine makes a lot of racket that sounds like something will fly apart. When I was a kid my Grand dad had a new Idea pull type mower and we were told to keep it at half throttle. Kinda stuck I guess.

Did the old steel pitman have a bend in it? Seems to me NI had a steel pitman on their mowers, I just can't remember which ones. Pine isn't a good substitute, as you found out. Use the oak ones. I thought my Uncle, a retired NI dealer, had said the wood pitmans were made of ash. Someone here should know. All of those mounting holes need to be in exact measurement to the original or there will be endless problems.

Another problem might be with the guards. The guards look like the non-malleable type. If so, they should have shims under the cutterbar by the bolt holes. If there are no shims, you may need to add a few to bring the front of the guard up so the the knife is a HAIR above the ledger plate (use a .013" feeler gague to check gap). That should improve your cut & reduce any binding under the knife.

You should also make sure your hold-down clips are holding the knife down. Not so tight as to bind the knife & firm enough to hold the knife close to the plate. Those clips also push the knife foreward to the front of the notch in the guard. They might also be too tight & binding or not pushing the knives all the way & plugging in front of the knife in the guard.

I learned the basics of operating a 30A behind a Farmall H as a kid & I agree that it was quite easy. What I didn't see was Grandpa, behind the scenes, cleaning, sharpening, adjusting & fine tuning. When I bought my first mower & had to do all of that fine tuning myself, I wished I was the kid on the tractor seat. I do keep up with the fine tuning, though, as I really hate to stop, unplug the mower, repeat.

P.S. If the book gives specs & clearences about the cutterbar & its associated parts, take the info with a grain of salt. Decades of use are murder on the tolerances & nothing will be exactly by the book i.e. the afforementioned clearence of .013" between the knife & ledger plate in some spots will be closer to .030".

Mike

Yes.......I think I may have been. Not too much more but I thought the lower gound speed and higher RPM would help. I assume this is not the right way to go.

Yes.....it seems to center OK.

If it's not binding like others have said I tape mine because when ever they've broke there was never anything there to cause the break so I figured they needed to be stouter. I tape mine with box tape because I think it's still a shear point. Got two years or better out of a stick. I was breaking a couple/three a season.
The other thing is the factory Ford has a pop rivet at one end to keep it from splitting along the grain, I drill the other end and put a bolt through it. It's through the wood before the last hole.

Yes....it slides easily with no binding. I may have been going too fast.....I was in 2nd gear on a Massey 35 but not sure of RPMs- maybe 7-800.

The broken pitman in the top 2 pictures had crooked grain..it split along the grain of the wood..
Keep the bolt holes as small as you can..
Appears that the Red clip is not down against the knife..?
Oil is your friend on these too..!
One small cross-bolt would be a good idea..
What kind of grass are you cutting..?

Ron.

Yours isn't pine. If you want a wood one make your own from white oak. However my Dad made his out of 3/4 pipe. Never broke again.

Are you keeping the bolts very tight? I had some problems, the bolts were coming loose & the holes would wear bigger. I had to double nut or use stop nuts on the many bolts in the pitman, that helped.

the break you show is 'odd', it's not breaking from binding, or the stick would break out of the way totally.

Hard to find good wood any more, maybe the bad grain?

--->Paul

Two things that come to my mind have already been mentioned but I'll mention it again.

Thurlow mentioned register. Was the last picture taken at the same time the next-to-last picture was taken. It looks like, from my angle of view that the sickle should be about half-way through it's stroke by the way the flywheel looks, but the knives are far from centered between guards. Maybe it's the view that's throwing me off, though. Is the pitman too long or short, making the pitman end of the sickle hit something when it's running up to speed? Is the head of the sickle too sloppy in the slides, allowing it to flex? That would cause more sickle breakage problems than pitman breakage, I guess.

PTO speed? Too slow and the sickle doesn't have enough inertia, especially for cutting fine grass. Too much PTO speed and the poor ol pitman just won't be able to take the stress.

Check out that red hold down clamp. Push the sickle toward the outer end. Then check and see if something is hitting. When I enlarge the pick I think I see where part of the sickle head has been hitting something. It might not be binding but if it is hitting it might evenually cause those bolts to shear. Also what Paul said those bolts have to be tight

I've heard of guys making pitman arms out of broken hockey sticks. They're pretty strong and better sticks could also have fibreglass on the shaft.

I sold hundreds of the 30 B mowers as New Idea territory manager. Do you have the right pitman stick and do not try and make one out of steel pipe.You cannot use just any pitman, They must be the exact length and the holes drilled right. It throws them out of register and you will not be able to buy them fast enough. If the pitman stick is right and the sickel and ledger plates are good it is a grass mowing fool. Go to a New Idea Agco dealer and get the right pitman stick. I am getting old and it has been a long time ago but I beleive the number was W20HSA.
gitrib

The round ball on end of the cycle bar has to be adjusted so that it will pop out before the arm breaks. check for correct adjustment.
walt

I have never ran a sickle bar at full PTO speed. You start out by slowly speeding up the engine until the sickle sounds the most quiet. Then adjust your ground speed to conditions. A MF 35 is at full 540 PTo speed at about 1600-1700 rpm on the engine.

Walt thats pure B S

Just a tidbit from my expierence. I was breaking thema s you described and looked just like that.......what I found was that after i put a new one on and tightened the bolts they had a tendency of working a bit loose after a few rounds. then it would break. So I tighten them then run a couple rounds then tighten again after broke in a bit.........have not broke one in three years now. Just check them bolts once in a while when you grease............jmtc

wayne

Your pix says the stick had a poor grain.Were the screws missing when it broke.One sure way to break a stick is to strike a rock with the end of the knife.Run the knife shoes as high as possible.The slip clutch will take care of grass binding.The knife has to be kept SHARP.Take a close look at the grain of the wood on new sticks.New pitman Sticks are 25 bucks here.Tsc only stocks blanks here at 12 bucks.I will make my own at these prices.Ash or white oak is the best wood.Hickory would be good but it dosent grow here.Theres a lot of labor in a pitman stick but prices are just too high.Your broken stick would have made a poor ax handle with it diagonal grain.Take measurments off your broken stick to make a new one.Making the hole for the latch spring will be the hard part.Years ago I needed new wood for the plunger on my baler.Dealer wanted 49 bucks for 2 hard maple sticks with a few holes in them.I said no thank you.I had a few hard maple planks up in the hay loft.I had the 2 pieces made in a half hour.At that time I could have bought a cord of ash fire wood for 49 bucks.Ash dosent weather well so it would be best to take the pitman arm off and hang it up under cover after the mowing is done.

YOUR GUARDS OR SICKLE are bad, putting too much pressure trying to push the sickle and or you are going too fast........Oh one other thing running tractor with foot feed and sickle not running fast enough when dropped in grass....My father wiped out 2 350 Deeres in one day buy running by foot feed....when clogged up and would let off and back up clean up and drop sickle back in and try to build rpms with mower trying to cut...sickle mowers are designed to run at pto speed or close.........

first of all,set your knife sections in proper register, you will never keep a pitman in it with improper register.then check lead, pull a string from in board end of pitman to end of knife section should be a straight line down center of pitman down center of knife head and straight down knife back if not youll never keep a pitman in it.next set your guards wear plates and holddowns correctly ,yours will never work because just looking at your one picture i KNOW youll never keep a pitman in that one because holdown has a 1/2' gap between holddown and sections allowing knife head to jump up and down! its simply rattling itself apart! my suggestion,quite honestly and i'm not being mean here,wait on manual before you break something you cant replace or repair.Its been so long since i used a mower like yours ,(i did run one for a long time and it was agood little mower),that I dont recall exactly how to set lead so i cant help you much,but I GUARANTEE THAT one will never run just looking at your one picture.hold downs are allowing knife section to jump up and down,allowing sections to ride over grass in guards binding it up,chances are wear plates arent snugged up either,i know leads wrong because your popping nuts off bolts on drive. if registers off it wont make any difference what you do .like I say i'm not being mean here,but youll never keep it together without cutter bar setup right,and the only way to know for sure how to do that is by the book and it has to be right, not close ,for cutting grass. grass is tough to cut with a sycle mower they have to be setup right and kept set,but once you get them working they mow very well and you can put a lot of grass on the ground in a days time if you have a smooth feild where you can keep tractor speed up.Heres the thing ,pto speed must be ran at mowers rated rpm,if you run less they bind up,in you run too fast they burn up.keep pto speed CONSTANT,on rough ground slow down by changing gears only leave throttle alone.if you stop pto ,back up, restart pto get mower up to rated speed and then move back into new grass.keep swath boards working correctly,board on end of bar should leave BARE GROUND or at least no cut grass to bind up mower head on next cut.set shoes correctly for height you need and dont raise cutter bar at corners.anytime bar is raised slow down so bar wont bounce. lots of tricks to these,but they will all be in your manual.good luck!i think when you get it setup right youll be surprised at how well they do cut and how reliable they are with careful upkeep.

another thing , see the grass laying on your knife head in your picture?that one thing will break a pitman more often than any other.its there because you have a piece broken or missing.just as there is a swathboard on out board end of cutter bar,theres one on inboard end.yours is broken off.its a rod that angles from front of inboard shoe and pushes grass or whatever your cutting away from knife head when its cut.look at bottom picture at front of shoe, you can see the stub of it where it has broken,bolted to inside of skid.make a rod the same diameter to bolt in there that angles over towards center of cutter bar long enough to make grass cuttings fall off knife head when cut,and you will stop a lot of your mowing problems.thats a very common problem with all mowers and it causes lots of problems.if you can get someone to take a picture of a good one it helps to understand.make two and keep one on hand.DONT!!!! take folks advice and make a pitman out of metal,please,if you cant fix it dont deliberatly destroy it which you can do if you put in a metal pitman.sell it to someone else who will fix it and buy a brushhog.

Thanks to you Jack and everyone else.....lots of good tips and advice. I will get this thing working right eventually. I don't give up that easy.