Since we already installed a number of rope pumps in the Netherlands, we were looking for a safety brake that is reliable and stultify the appearance of the rope pump not too much. As users rope pumps knows, the wheel and handle swings back firmly as they stopped with pumping. In developing countries the user get instructions to use the hook to prevent turning back of the handel. For public places where anyone can use the pump, the blocking hook will not be used and there is a change injuring the user.

Therefore our search for an automatic device that prevents the reversal movement.

Already been experimented with a kind of rattle that stucks in the spokes of the wheel. Tests showed that the forces where so enormous that the rattle pin bended. Another solution might be a band brake. This is also tested. Alongside that it is vulnerable to vandalism and this looks not so pretty, the braking power is not sufficient and reliable enough. A third type of a oneway brake with a nail into a wedge-shaped space in the bearing bush gave good results being better than expected. The video shows the pricipele operation, construction and testing of the oneway brake.

The days are starting to lengthen and temperatures rise. And on the WOT-field the nature has actually been in effect. Sometime in the distant past on the back WOT-field by a WOT member with very green fingers has planted daffodil bulbs. And miraculously come each spring the daffodils appear in the open field for us to cheer.

After a quick experiment with a drill, an asynchronous electric motor, a capacitor and a lamp, we got the idea to build a generator. The aim was to connect the 3 kW electric motor to a 3.5 hp Briggs & Stratton petrol engine from a lawn mower. We fabricated a frame where both engines can be put down in two evenings. We took some pullyes and a v-belt for the transmission. The electric motor is fixed with wire ends, so the v-belt can be always be set tighter.

After cleaning up the engine the combination works perfectly. Only some vibrations appear caused by the engine. Perhaps the pulley must be fasten tighter or a damping suspension is needed. After that the capacitor must be connected to provide power. More news about the homemade power unit coming soon.

The lamp, we spoke about in the first sentence, had not a long life: After a high number of revolutions and huge light output the 60 watt bulb broke down.

From the Department of Thermal Engineering (ThW) of the University of Twente we got three gas cylinder carts for free! Ideas about what to do with it were found easily. One cart will be modified into a trolley and the other two will probably be combined into a convenient caddy.

On Sunday, January 23rd, Freddy and Rene went to Utrecht to install a rope pump at the patting zoo ‘New Rotsoord’. This pump is the very first sample of a new design: the pump has a single support instead of a whole frame. As a result, the material costs drop 20 percent and the design becomes simpler.
The construction of the pump was done in Enschede. The only thing necessary at Nieuw Rotsoord, was the installation of the pump.

The pump is placed in a concrete foundation next to a 6-meter deep well. The intention is to let the volunteers of Rotsoord make a drive gear based on a bicycle.

Once we receive a picture we will definitely post here.

It’s Christmas time! Like many buildings, the WOT site got a makeover too last week. Thousands of Christmas lights bring magic to the place.
No doubt about it: all lights are LED’s!

It’s worth watching it, especially in snow.

The WOT 12PU500 windmill is being constructed in Biratnagar (Nepal). Students from Pulchowk Engineering Campus are building the windmill for local farmers, who use it for irrigation. Besides the windmill, students have developed a Hybrid Solar Dryer that can be kept warm by wood if there’s lack of sun.

Katrin Shrestha and Brecht Mommen from Nepal visited the WOT last week. They showed us a film about running projects in Nepal. You can watch several projects too; have a look at the website of Clean Energy and Learning Centre .

Quite a large number of T-Week participants are students studying for tropical doctor. To ensure this number won’t decrease the WOT was represented at their Career Fair today. It took place at the LUMC in Leiden. WOT member Mark Westra tried to convinced the 160 students the T-Week would be a valuable experience.
Most students had heard of the WOT before and few of them already joined the T-Week. (Even parents of some students had participated, 30 years ago!)

The smell of melting iron filled the Kiwanda last Thursday night. Menno-Jan and Freddy gave a workshop welding to three students.
After a brief explanation and some cautious trials the three students were allowed to weld all by themselves. By applying tips and advices from Freddy and Menno-Jan their welding become better and better. Their first welded dice soon became a fact.
By the time the workshop was full of smoke the students could demonstrate their acquired skills by welding a watertight cup.
One of the three proved to be watertight. The proud owner immediately upgraded the cup to a tankard.