Mahindra 3616 blower broken shafts

[Lew3616]

Have a question, I have a 3616 with the 66" SB66 front mount blower, I have had to replace the gearbox input shaft 3 times in the last 2 years, it broke again only after 5 hrs of running time, this will be number 4, it breaks where the shaft steps down for the steel worm gear. Dealer says I wasn't running it at the correct rpm, so I ran it at his recommended rpm, I broke a shaft, then he says I need to run his shear pins, and thats why it breaks the shaft, the first time it broke I was running his shear pins. When I got the blower new, the drive shaft was out of balance, he replaced it, a few weeks later the bearings all came loose, nothing but problems with this blower. Any ideas of why the shaft keeps breaking? Thank You.

 

[JerryK]

The sub-frame and blower are sourced from Bercomac in Quebec [ Bercomac - Accessories for Lawn & Garden Tractors, ATV, UTV and compact & sub-compact tractors ] ... You might want to contact them and ask them if they have an idea. I have a 78" blower on a 2555 and a 1526 with a front blade. All are made by Bercomac and seem to be built like a tank, have had no problems with them. I had my blower apart checking the gearbox oil level, and I think it was an generic ag Italian gearbox, but my 78" might have a larger/different one than what they put on yours. If you have your sub-frame and blower manuals... I'd go thru the original set-up instructions and make sure everything is put together as it should be. The sub-frames are made to be put on several sizes of tractors and can be assembled to fit each. I'd make sure that the front drive shaft [ the one running from by the front axle to the blower shaft you are breaking ] is phased correctly. Google drive shaft phasing if you need the info. And also check that it is not hitting on anything when you lift/lower the blower. You might want to check that the front driveshaft is also not bottoming out [ too long at any point during the raising/lowering. ] If the main underneath driveshaft [ the one with the shear pin ] sticks out too far forward, that would make the shorter front driveshaft bottom out, too. Good luck, Jerry....

 

[pmsmechanic]

As above.

 

[JerryK]

It looks like the front shaft can [ or should ] only be assembled one way, so that should negate a phasing problem. When you get it all back together, see if you can unhook the driveshaft quick connect [ #2 in the second picture ] from the main driveshaft [ # 3 ] and get some forward movement showing that the front shaft has some elbow room and not pressing forward on the gearbox. If so, maybe the main shaft is sticking forward too much. Only other thing I can see is if the access cover that is above the shear bolt area is put on using the wrong bolt holes, and sticking out too far forward keeping the driveshaft from lifting up enough. You might want to check the phasing of the rear shaft going to the MidPTO gearbox. There should be no vibration to speak of, a little noise, but nothing bouncing around.....

 

[Lew3616]

This is my blower, parts breakdown, the shaft that breaks is the shaft with the arrow pointing to it, it breaks inside the gear box.

 

[Reb954]

The shaft is breaking inside the gear box so according to your diagram that is after the impeller so that rules out the impeller being part of the problem. Check how free the auger is rotating. Make sure you don't have bad bearings on the end(s) of the auger and that the auger shaft is straight inline with the gear box. If the ends of the auger shaft are not lined up to the gear box, that could be jamming the gears together inside the gear box.

I would also contact the manufacturer, let them know what is happening and what you are doing with the blower. How deep is the snow, how wet or dry the snow is.

 

[JerryK]

That blower is entirely different than my 78". I have a gear reduction box fed off the front pto shaft whilst yours uses a belt reduction. I thought you were breaking that shaft going into the main reduction box. Mine does not have a gear box in front of the impeller, the auger is chain driven. [[[[ sorry ]]]] I will go crawl back into my hole.....

 

[Lew3616]

JerryK, you have been very helpful, you all have, I contacted Bercomac, left a message, the gentleman called back in just a few hrs, wants pics of the blower and other info. He asked me to check a few things, then go from there. Thanks all

 

[JerryK]

Please send all donations to the JerryK Tractor Acquisition and Operation Fund..... [ and THANKS....!!!!!!!!!!!! ]

 

[pmsmechanic]

Ok so I'm going to stick my neck out here a bit. If there is any vibration in the pto shaft it will be absorbed by the belt. I'm assuming the pto drives the bottom pulley.

If I understand the drawing correctly that shaft has the top pulley and the impeller and the gear box on it. There are two bearings one on each side of the pulley plus one where the shaft goes through the blower housing just before the impeller. The two bearings fit into part number 9. I can see where the bottom bolts go that hold the two number 9's together. That would be close to the number 73 on the drawing. Where do the top bolts fasten to?

To me it looks like there is enough going on in this area that there should be a specific order in which to tighten up bolts and bearing collars etc.

I would say make sure there is no binding when part number 23 is tightened up. Or maybe there is some flex happening under load in that area. Also when bearings number 8 are installed the bolts should just fall into place. There should be no prying anything to install them.

If it was me repairing this I would cut and install a flex joint in the shaft that your arrow points to. Something like a LoveJoy coupling would do the job. Or two sprockets back to back with a double roller chain coupling them together. Something to isolate any impeller shaft misalignment from the gear box shaft.