The set up

The set up
5.46mm jet delivering 0.68 l/s to the pelton which is rotating at 900 rpm and generating 135 watts into the grid.

Tuesday, 30 June 2015

Another set of bearings on trial

Some things just don't work out as you hope: - today has seen the end of the ceramic bearing trial after just 28 days of continuous running.

Over the past week I had begun to notice a rumble coming from the Powerspout rear end and last night it became a more unhappy noise. As the turbine came to rest after shutting down, there was a clearly audible clicking as the shaft came to a standstill.  On inspection this morning, there was palpable free play in the shaft, - not much, but after so short a time, it was not worthwhile continuing the trial and risking a major bearing failure with damage to the Smart Drive rotor and core.

Michael Lawley commented when I told him about it that he had always had concerns about ceramic bearings, - "the only people who seem to use them are skate-boarders who would be lucky to do 100 hours".

So this morning was spent putting in a new bearing block, this time with SKF E2 Energy Efficient bearings.  I plan to run these with just their factory fill of grease, not adding any extra grease via the grease nipple.

Here are a few pics of doing the replacement to illustrate: 

  • how tightening the runner retaining bolt can be a one-man job 
  • a homemade tool for accurately aligning the runner to the jets:

Home-made tool to lock S-D rotor 

Tapping lugs into place in the holes in the rotor

Tightening to 38 ft lbs with the shaft locked

Piece of pipe which is a tight sliding fit in the nozzle holder,
with two wood inserts each end, bored dead centre
to take a 4 mm knitting needle

Device in place in bottom nozzle holder after removing nozzle

Close up of needle point on splitter ridge with just the
right number of packing washers behind the runner
to have the jet divided equally in two by the
splitter ridge. 


Magnus and Konswan Johnson said...

Good idea with the knitting needles, I'll have to try that.

Bill said...

If you do, there's no need to make two. I only ever use one. Looking at your turbine installation, it is like mine where using the sighting method which EcoInnovation suggest isn't really feasible if you can't easily detach the manifold pipes. That's when the knitting needle comes in useful.
Nice to read of all you're doing there on Flores. All strength to you !