Replacing the windmill shaft

Roman explains here why a single piece windmill shaft that interlocks with the pinion gear at its end is a preferable option than a three-piece mechanism where the parts are joined by welding.

In order to improve performance Roman manufactured with a lathe (torniyo in Tagalog) a single-piece shaft whose head ends with a toothed head that engages the pinion gear (known sometimes as drive gear).

Avoiding welded joints Roman tries to prevent the shaft from wiggling, and progressively bending until complete failure of the pumping mechanism.

Roman highlights here that his solution is more expensive but potentially more durable.

Why the windmill shaft warped

The crew of farmers and workers who took the wheel down from the windmill examine now the problem that forced us to replace rotor’s shaft and pinion gear.

The issue lies squarely on the flawed connection of shaft, lubricant case and pinion gear. By welding three separate parts, relatively weak joints had been created: eventually, the fast rotation of the wheel warped the shaft.

Understanding the causes of this failure is essential to optimize windmill technology, which has been recently introduced in the village. Increased reliance on wind energy depends on its adaptation to the village context, and broader local know-how about construction, maintenance and repair.

Getting the fan off the windmill

The windmill tower is 50 feet tall. It carries the fan on its top: a multi-blade wheel sitting above the canopy formed by the crowns of old mango trees. Our fan has 20 blades – also known as “sails” – in galvanized iron (1.4mm gauge), and a diameter of almost 3.5 metres. The fan is attached to a shaft: the shaft rotates, as the fan revolves pushed by its ‘sails; and this motion turns a pinion gear inside a gearbox on the opposite side of the shaft. The uppermost tip of the rotating fan reaches a height of 55 feet.

Even with minimal wind, the fan and its 20 “sails” make up a very heavy frisbee.

To replace shaft and pinion gear we had no other option than getting the wheel off the tower. Not an easy job: it took eight people to take it down, dismounting the fan from its shaft above the tree crowns and descending it 55 feet below.