|
|
Wangaratta, Victoria, Australia | We bought a new h 7230 disc bine and have done 400 acres and the back bolt that holds the first disc hub together has sheared off.
We do not believe that we have hit anything hard enough to do this.
Has anyone else had this happen.
The broken bolt lead to miss alignment of the drive shaft putting side load on the splines cutting bot the drive shaft and module splines out.
The dealer does not think CNH will warrant this.
These bolts hold the cutter together.
Edited by lino 10/24/2015 01:19
|
|
| |
|
central ohio..between Springville and Millbrook. | Have had it happen 3 times this year.
I don't know why they break but I have taken to checking that twice a day and keeping a few of them on the shop shelf
Good luck!
Josh Moorefield
Moorefieldhayfarms.com |
|
| |
|
nw iowa | first year we had ours the bolt broke and they gave us a new bolt under warranty, we didnt need the drive shaft that time only the bolt |
|
| |
|
east central GA | One reason that the bolts break is that the big tension springs are not tight enough causing the mower to drag two hard on the ground. The operators manual tells you how to set the tension. |
|
| |
|
| As long as the machine is still under warranty, NH should approve the repair. Pay attention to the dowel pins in the spacer and the end cap as well as the dowel holes in the module. If you operated the machine long enough to strip the splines, the dowel holes are probably elongated. If the parts do not line up properly on reassembly you will strip the splines again sometime in the future.
While your dealer may not have seen the failure before, it does happen. He has nothing to loose by submitting a warranty claim except his time. If he refuses contact NH.
|
|
| |
|
Wangaratta, Victoria, Australia | Thank you for your replies do you all think that something is shearing the bolts off or are they failing for another reason.
I had not thought about incorrect down weight of the suspension springs but they are set so the cutter is not held up after going over a bump about 50kg required to lift it off the ground. |
|
| |
|
| While the weight being carried on the cutter bar may have an impact on the longevity of the tie bolt, it alone is not the reason for the failure. This is strictly my opinion why the rear tie bolts fail. If you look at the end cap where the tie bolts go through you will see the width of the cap is about 5/8" narrower than the front. When you tighten a bolt you are actually stretching the bolt and are relying on the stretch to hold the nut tight. The tie bolts are 3/4" rod with coarse threads cut on each end. In reality you end up with a 3/4" rod in the center of the bolt and 1/2" rod where the threads are. So where would you think the stretch of the bolt is going to happen. It happens in the place of least resistance which is the threaded area. The front tie bolt has about an inch of threads between the nuts where the stretch can happen. The rear tie bolt has about 3/8" where the stretch can occur. Both bolts are going to stretch the same amount but the stretch in the rear tie bolt will be concentrated is a much shorter length of the tie bolt threaded area when compared to the front tie bolt.
That alone would not cause the rear tie bolt to fail. After all the right side has the same setup and all the failures I have seen are on the drive side. I believe the added torque of the drive on the first module is also exerting a pulling apart force on the tie bolt. The strange part about the problem is that it is more prevalent on 9 ft machines than the 10 ft machines. And on top of that, the problem is on only a few machines. On the ones I have seen fail, header floatation was not an issue at all. I set all machines all the light side when attached to operators tractor.
I had one machine that failed that tie bolt 4 or 5 times and it would fail with less than 20 acres of use. I thought I would test my theory about the bolt stretch and upon reassembly I installed 5 additional washers on the rear tie bolt so the nuts were in the same position as on the front tie bolt. The machine has now completed three seasons without another failure. In fact none of the units I have done has failed again. Use only the correct washers and nuts and follow the procedure from NH on reassembly.
I would also replace the bottom gear box seal. When the cutter bar separates it opens the gap between the bottom gearbox hub and the hub on the drive shaft. This allows material to enter below the gear box seal. Have only had two gear box failures on the 9ft machines but both machines had a previous tie bolt failure. I now at least check to see if material has packed around the seal.
Edited by mike10 10/25/2015 09:10
|
|
| |
|
Wangaratta, Victoria, Australia | Mike by bottom gear box seal do you mean the seal under the cutting disc. We replaced the first module and the seal in the second module.
I did notice the difference in the width of the cap and feel that you have a very good explanation of the problem.
What is your background farmer or mechanic.
I am not sure if the correct assembly procedure was followed as I just let the NH mechanic do it and I helped when he needed it. He did seem as though he was very competent and knew what he was doing. |
|
| |
|
| The bottom seal in the large main gearbox above the cutter bar drive shaft. The gearbox that drives the cutter bar. |
|
| |
new holland h7230 problem
