Visit to Veldkamps Meul'n in Bellingwolde
Today I went back to Bellingwolde to make pictures of a windmill there that is still in operation.
The miller, mr. Enkie Kok allowed me to go all over the machine, built in 1855. It's a 20 meter diameter 4 bladed rotor in the 'traditional' dutch design but this one has a good number of peculiarities.
For instance, it has remote controlled brake flaps and a friction based hoist to haul the sacks of grain from the ground floor to the mill stone level.
Here is an outside view of the mill. It's a *huge* structure, the only building taller in Bellingwolde is the church. You can clearly make out the altitudes of the various floors in the mill, not all of them are 'full standing height', so it's pretty easy to bust your head on some 150 year old oak crosser.
A second front view, this one shows the blade pitch better. In dutch we call this a 'boven kruier', the yawing part is only the very top section, the yaw beams and gear are at the back of the mill, you can just make out the yawbeams sticking out left and right of the head of the mill.
Contrary to the 'fieldlines' windmills this mill carries sail on her blades for extra power during low wind, but if the wind is up then the mill works just fine on the flaps alone. Power is regulated by turning the flaps flatter (more speed) or coarser (less speed).
The miller on the landing, respectfully away from the moving blades and keeping a sharp eye out. The blade assembly weighs multiple tons and it moves at german autobahn speeds at the tips. This is a machine built well before OHSA and it is very unforgiving with people that make mistakes or that are careless. There is also no 'undo' button.
A view from directly under the mill, here you can see the blade pitch even better. You also get a reasonably good view of the flap actuator mechanism which runs through the centre of the main shaft.
This sign is a word to the wise, you enter this mill at your own risk. This is a working machine and the miller has only two eyes. Also the masses involved mean that it takes some time to stop the mill once that decision has been made (and if the wind cooperates).
A spare crawl wheel that moves the mill over the yaw axis.
Assorted bits and pieces of industrial heritage, as well as a fire extinguisher. The reason it is there is because most of the construction of the mill is in wood. The main cause of death for these beautiful machines is fire through runaway. If the machine should become unstoppable then the bearings will sooner or later overheat and then fire is a real risk. Also some fool might decide to light up despite the no smoking signs everywhere.
Two beautifully carpentered crown wheels, the teeth are held in from the back. This mill has all kinds of extra wind powered goodies and assemblies like this are bolted on to every available surface on every floor.
Top view, note how nicely the gears mesh.
The belt drive running off the two wheels which could be used to power high speed tools. This mill makes about 18 KW of usable power, plenty for industrial power tools.
The main end product of this machine was flour, and it went by the scales to make sure the miller got his bit.
The flour chute, flower was bagged on this floor and then sent down to the waiting carts.
One of the millstone assemblies. The grain was poured into the box on the right hand side and then shaken down the chute underneath it where it fed into the center of the millstones. The top millstone has a fair sized hole cut in it where the grain falls through to the gap between the two stones. They have spiral grooves cut in to them in such a pattern that the grain goes to flour by the time it reaches the outer rim of the stones where a little wiper causes it to drop into the exit chute under the stone assembly. The big piece of steel with the two shaft ends sticking out at the bottom is the stone hoist, the stone was periodically dressed using a special hammer and for that purpose the top stone was hoisted off the bottom one and then flipped over.
The millstone assembly when it's opened up. The little leather wiper is all that it takes to drop the flour down the bagging chute! This picture was not taken by me but by the miller the last time the millstone assembly was open for maintenance.
The other millstone assembly. This one was rebuilt and is not currently in use because one of the pin gears is not on it's shaft. This mill was built up to be working on both stones at the same time, maintenance was alternated between the stones so the mill was ready to work continuously.
Another one of those clever bits, every floor up to the mill level has these flaps in the ground which can be set open. A bunch of ropes runs up and down the mill to a hoist on the next level up, which is powered by the mill. Pull one rope and the drive engages to lift, pull the other then the drive disengages and gravity will do the reverse. It's quite clearly visible that each and every bit of work that could be mechanized was done away with to lower the amount of work that went into milling a pound of flour. This really was the beginning of the industrial revolution with machines taking over from manual labour. And with 0 pollution to boot !
A view down the throat of the millstones. You can see the film of flour covering every surface inside the millstone assembly. If you look closely you can see that the chute that drops the grain is manipulated by an excentric on the shaft, which causes the grain chute to move to the left. Then when the shaft continues to rotate the spring will pull it back shaking a bit of grain into the stones at every stroke, nicely coupled to the RPM of the rotating mill. That way no matter how much wind was available the grain would not overfeed the stones (which would cause the mill to stall).
The yaw mechanism. When you turn the wheel by the spokes it winds steel cables on and off the shaft, which pulls the mill around by the boom. To spread the load on the movable section of the mill there are four sturdy beams running to different sections of the carriage. Here you can see how high the mill is in comparison to the local buildings. And you can - unfortunately - also see how dense the surrounding vegetation is, which leads the mill to be in quite turbulent wind.
The 'remote control' section. The right hand side lever is the friction brake, the left hand side one is the one controlling the variable flaps on the blades, this will move a rod through the center of the shaft.
A close up of one of the flaps, in the 'coarse' (slow) position. Today it was dry, fortunately. Last time I was up here a week ago the floor of this level was slick with algae, and it was quite hard to keep your footing.
Another view of the flap, from the other side. You can clearly see the control rod that sets the flap position, as well as the lattice for the rest of the blade where the sails strap on to. These sails are used for extra power in low wind.
The master of the domain, Mr. Enkie Kok. He's dressed for the occasion, it is *really* cold up here in the wind. He runs the mill all by himself, but if you would do real production with this mill you'd have to have a helper. There is simply too much going on on the various levels to operate this mill on your own. For instance, the controls are at the level of the stones, but the bagging happens one floor lower.
A close-up shot of the hub of the mill, you can clearly see the flap control rod, right now it is all the way 'in' to the shaft. Notice all the tricky linkages, as well as the ingenious use of wedges to hold the blades in the core of the hub.
Another view of the hub, now with the flaps control rod 'out', this sets the mill to operate at a higher speed. Compare the difference of all the components with the previous picture. Also a really nice view of the blade curve.
And another side view of the flap in it's new position.
A pin gear and it's regular mate. This speeds up the rotation of the mill 7:1, the right hand side gear has had a woodworm visitation but is still quite sturdy.
An overview of the gear, it's too large to make a single picture of it because you can not go back far enough in the mill without running into the wall. This gear is about 12' or 4 meters in diameter. The gears are again both prime numbers so every rotation one gear tooth sees a new geartooth on the other to even out the wear. It runs surprisingly smooth. I was at this level with the mill in operation and it is just amazing how evenly it all runs, but at the same time it is very scary. The gears are absolutely unprotected and there is only a very narrow area where you can stand without being 'caught' by the very fast moving gear teeth. The wheel moves so fast that you can not make out the individual teeth.
A close-up of the gear teeth. Apologies for the blurry picture. Note the cobwebs coated with flour, and the smooth wear patterns on the teeth and how small an area on each tooth is actually in contact with the other gear.
A top view of the friction drive for the sack elevator. There are no teeth on this at all, nothing has been done to roughen the surface, it's just two wooden wheels touching. The hoist shaft is sticking out on the left in this picture, and the beam in the left front running between the wheel and the shaft is the actuator for the elevator.
A close-up of the friction drive. The hardwood friction elements on both wheels are a wear article.
The actuator arm for the friction drive. It simply drops the one wheel on to the other, the load of grain on the shaft helps to increase the friction. One end of the shaft is hinged, the other runs in between two posts.
Here we're in the top floor of the mill. This is a rear view of the main gear directly on the blade shaft. The secondary shaft is a huge tree that has been roughly dressed square and reinforced with steel clamps against splitting by torque. The second gear is also steel reinforced, which allows the teeth to run close to the edge. Here the speeds are still low enough that the torque is enormous and it shows in the wear pattern on the teeth. Note that theis mill is geared *up*, not down, so shafts are progressively weaker and thinner as you get lower in the mill (but they turn faster). The piece of wood on the left hand side of the main gear is the friction brake, which is tightened around the outer edge of the main gear.
Another nice view of the main gear, as well as the cast shaft running through the center. This mill had a runaway a short while ago, there was a fruitfly infestation in the area between the brake and the main gear, but because that's a very tight space it is not easy to see in to it. At the first attempt to brake the mill the brake was lubricated with FruitFly Brand jelly which made the brake completely useless. The miller managed to halt the mill by yawing it out of the wind and was quite surprised that small insects can have such huge consequences! A run with some cat litter between the gear and the brake cleared the matter up and now everything is back to normal.
This is a view of the flap actuator mechanism. The side pushes the rod in and out of the shaft running away to the left depending on the position of the control bar at the back of the mill. The flaps were a modification to the mill from it's original design, and the hole for the actuator rod was drilled by the mill itself. Not a bad job over more than 12' (4 m) of cast iron shaft ! The hole is dead center at the back and out by about 2" (5 cm) in the front. All the grease is strictly organic, pigs grease and such are a staple supply for the mill. Especially in warm weather it can get quite smelly here.
Another view of the massive shaft running out the front. You can see the backward angle of the shaft clearly in this picture, as well as the evidence that birds like to sleep here.
A nice bit of woodworking here, the cover of the mill has the most intricate shape worked out in small pieces of wood on curves. With every piece the angle changes ever so slightly.
The main bearing of the rotor. That shaft is about 40 cm or 1'4" across, and it is by far the larger amount of the metal in the mill. For the rest it's mostly wood and brick for the outside of the structure.
Main bearing greasebox
And another view from the right hand side.
In this picture you can see how tight the clearance between the main gear and the brakeshoe really is. We're looking at the front of the main gear here, each tooth held in place by it's own little wedge. This is extreme carpentry, done without any power tools, just chisels, saws and craftsmanship.
A close-up on one of the wedges, apologies for the blur...
The difference between 'brake on' and 'brake off' is hardly visible...
The business end of the brake.
When the mill is not in use the friction brake is not enough to guarantee safety, so this permanent blockage is pulled into the main rotor to stop it from slipping it's moorings and taking off on a night run all by itself.
The wedges that fit the secondary gear to the shaft. This all has a temporary feel to it because running this machine on a permanent basis is a continuous battle against wear and tear and rebuilds (partial or more substantial) are a fact of life.
The driveshaft of the millstone.
The millers certificate of the ability demonstrate the theoretical and practical knowledge necessary to operate a windmill. This certificate not only gives the miller the right to operate this machine, but ever other windmill in the netherlands.
After making the pictures we stood around for a while to talk some more about milling and all the time that we talked the mill was simply asking to be run by continuously tugging on the brake and the gears, when the machine operates the whole building speaks with the voice of the mill.
I hope you liked the guide tour, if you ever wish to visit the mill in person, it is open to the public on Saturdays, the location is:
Hoofdweg 314
Bellingwolde