Archive for 2011

Innovative freewheel clutch for rope pumps

Wednesday, May 18th, 2011 2 Comments

A directional brake

A directional brake

Since we already installed a number of rope pumps in the Netherlands, we were looking for a safety brake that is reliable and stultifies the appearance of the rope pump not too much. As users of rope pumps know, the wheel and handle swing back firmly when they stop pumping. In developing countries the user gets instructions to use the hook to prevent turning back of the handle. For public places where anyone can use the pump, the blocking hook will not be used and there is a chance of injuring the user.

Therefore, we searched for an automatic device that prevents the reversal movement.

We have already been experimenting with a kind of rattle that inserts in the spokes of the wheel. Tests showed that the forces were too high resulting in bending the rattle pin. Another solution might be a band brake. This is also tested. These solutions do not look very pretty and they are susceptible to vandalism. Also, the braking power is not sufficient and reliable enough. A third type of a one-way brake with a nail into a wedge-shaped space in the bearing bushing gave good results. Better than expected. The video below shows the principle operation, construction, and testing of the one-way brake.

Spring on the WOT-field

Wednesday, March 23rd, 2011 No Comments

Daffodils in bloom at the Kijito

Daffodils in bloom at the Kijito

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.

DIY Power Unit

Saturday, March 12th, 2011 2 Comments

3kW generator lawnmower engine

generator in the making

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.

ThW donates gas cylinder carts

Friday, March 11th, 2011 No Comments

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.

Three cylinder carts in a row

Three cylinder carts in a row

Installation of rope pump in New Rotsoord, Utrecht

Wednesday, February 2nd, 2011 1 Comment

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.