Life at the end of the road

March 10, 2008

A day up the mast

Filed under: daily doings, life off grid, wind turbine — lifeattheendoftheroad @ 9:06 pm

Having been hearing all day yesterday about the impending storm of the winter I was somewhat relieved when it didn’t venture this far north. In fact it was a bonny dry day, grey but after all the rain and showers of late, bonny. Did all the usual morning stuff then decided to check out our small wind turbine as I’d been hearing a vibration through the tower, it’s performance seemed lacking and it was needing allot of wind to start it. Sure signs of bearing trouble, which if left unchecked can lead to blade failure then self destruction ( I speak from experience ). I have a love hate relationship with my ‘Rutland 910FM’ 12v turbine, I love it because I’ve had it 18 years and it kept my house lit in the darkest of winters. Having said that it’s a bit like the 40 year old broom that’s had 6 handles and 12 heads, which is why I hate it because I’m forever repairing it. Had I not been given half a dozen old ones that had been used to power ‘seal scarers’ on salmon farms I’d have given up long ago as they stopped making parts for this model 10 or 15 years ago. They upgraded it, made it stronger more powerful and quieter around the same time as they stopped making the older parts but to be honest it wasn’t much better. I had one of those too, it lasted longer but failed more spectacularly than the older model, I picked up bits of the blades over a hundred yards away. Nowadays there are far better cheaper wind turbines than Rutland which is a shame because they were one of the first and they’re British, they just don’t seem to have moved with the times. I’m all for sticking with something that does the job and if it aint broke don’t fix it which is why I drive an old Landrover but the Rutland is plainly not designed for Scotland.

Overhauling a ‘Rutland’

First thing I did was put on my crash helmet, safety harness and climb the 40′ mast in the vain hope that it was something caught behind the hub. No such luck, on arrival at the top I was dismayed to feel play and stiffness in the rotor and signs of wear in the yaw bearings.

910 rust

The brown stains on the black body is caused by rusty water from dry needle rollers that allow the turbine to turn in and out of the wind. Next step was to tie off the rotor to stop it setting off and giving me a hair cut, then it was back down the mast for tools and rope to lower it.

Once unbolted, lowered and carried into my workshop it became apparent that it was in poor shape.

slip rings 910

As you can see the top slip ring is burnt because the carbon brush cap has come off. The needle rollers were dry and rusty in the bearing that sits below there and one of the bearings in the hub had gone. Fortunately I had spares and it’s quite straight forward to do everything apart from the needle rollers which I just intended to clean up anyway and fit a grease nipple to prevent a repeat performance.

The first thing I always do is mark all the wiring, disconnect the 4 that go to the altenator undo the 2 8mm locking nuts and bolts that hold the spindle on its support then slide out the hub assembly complete. It’s then a simple mater to undo the 12 screws and 6 nuts and bolts that hold the hub and blades together. You can then insert two of the long screws in two holes at the back of the hub and screw it apart, marking the two halves first so they go back in the same position.

hub split

The stator can then be carefully pushed out of the hub and it was this bearing on the back that had failed, the easiest way to remove these ( I’ve done loads ) is to crush the outer race in the vice, prize off the balls, carefully grind a flat on the bearing then twist it off with a 19mm spanner giving a bit of gentle  help with a screwdriver behind the stator.

stator 1stator 2

After carefully fitting the new bearing i coated the inside of the housing where the outer race sits with ‘loctite’ as they’re prone to wearing out the composite of the hub if they come loose. Though I’ve repaired these in the past with shim steel. I did remove the yaw bearing housing clean up the needle rollers with WD40 and oil before drilling and tapping the housing to take a grease nipple then filling it with grease (but I’ve deleted the pics!). Once reassembled I put a meter on the two wires and gave the hub a spin, much to my amazement it worked! (again lost pics). Then it was back up the mast, me pulling and mrs C guiding with another rope to clear the guys. The turbine was then dropped on its mount and tightened up. This can be very tricky if your an idiot like me who did not make his mast so it could be easily lowered for servicing so I made my electrical connections so you can secure them once the turbine is bolted up. I have in the past assembled it in three pieces up there, body, tail then hub, but now I just tie the blades to stop them turning  fasten myself securely to the mast with a safety harness, have the tools I need in a belt and just do it.

fitting Rutland

By the time I’d done all this it was almost 4:00pm, the Dude was home from school and I’d had enough of wind turbines for the day so he and I went out for a bit of target practice and the chance of a bunny. We were out of luck on the rabbit front but spent a good few mins watching a bonnie stag through our telescopic sights before returning home for dinner.

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