Wheels and Brakes

just bolt them together. It sounds simple but it didn't work out that way. I had to melt the first casting out with an acetylene torch to get it out of the mold. I tapered ...
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WHEELS AND BRAKES By Alfred H. Rosenhan

I brake building project when I joined Chapter 23 in had no idea that I would be involved in a wheel and

Salt Lake City. I have always been interested in building airplanes and was making plans to get one started. My

brother and I had built and flown (many hundreds of hours) a Corben Junior Ace in the 1930's. I made a set

of hydraulic brakes that fit inside of the wheels so I had a little previous experience on the subject. I decided a 4x7 tire would give me just the right size wheel for a little single seater. This would give a 15 in. outside diameter wheel and I planned to make a nice streamlined wheel with the brakes inside like I had on the Corben.

dump many a casting back in the furnace because the metal was not hot enough and wouldn't fill out the casting.

I have been getting ahead of myself. I should tell about my furnace. I bought a graphite crucible that will

hold about 50 lbs. of metal. Then I hooked up a gun type oil burner. I cut a 50 gal. oil drum in half and lined it with fire brick, leaving room between the brick and drum for about 1 inch of sand. Then I put about 6 inches of sand in the center and set my crucible on a brick

broken in half and doubled to give the crucible about 4 inches of clearance above the sand. This arrangement left enough room around the sides for the heat. I placed broken fire brick around the top to keep the crucible centered and to let the burned gases escape. The first time I fired up was in my basement. I found out two things. 1st, that the oil burner would not get hot enough. 2nd, I had to move out of the house. (I smoked up the whole house and got all the drapes smoky. My wife was very unhappy). I had to take care of

This is an exploded view of the 4x7 showing all grease seals and bearings and brake parts. When these wheels are assembled they are plumb full of machinery — and not much else.

I planned to make steel molds so I could make as many as I wanted to. So I started to cut up and machine and weld up my molds. I had to allow for shrinkage in my molds (aluminum shrinks ¥4 in. to the foot when it cools). At a chapter meeting one day, several members who were building Cougars, Tailwinds, etc., complained that they couldn't find any wheels for their airplanes and that

new ones were very expensive. I found that a good many plans call for 5x5 wheels and brakes. Well, I really stuck my neck way out. I had never let shortages bother me much. If I couldn't find what I wanted I made it! (My brother and I cast and made up a set of ball top pistons for our Salmson that we had in our Corben. It got us over the fence quicker and gave us 50 more top rpm). I offered to make some 5x5 wheels for them. I borrowed a 5x5

the second problem first and move everything to my place of business (my brother and I run a garage and body building business). I took care of the first problem by changing to natural gas. This I did by taking out the oil pump and pipe and nozzle and drilling a hole in the back and putting in a % in. pipe. It works very well. I first used scrap aluminum for the castings but I soon found that to get good castings you had to use good material. After some investigating I learned that No. 356 aluminum alloy was the best all around material to use. It worked well with steel molds and later on I found it could be heat treated to a T-6 condition. This makes the castings tough and doubles the strength. I now have all wheels I make heat treated. It took about 9 months of spare time work to complete the first pair of wheels and molds for the castings. I found that the most time consuming operation was the brakes. I first cast them separate with a steel liner and then riveted them to the wheel. This also took too much time. I made an attachment to the mold that holds a piece of 5 in. tubing 1 3/16 in. wide in place and casts the brake drum right with the wheel half. All I have to do to them is to take a truing cut and cut the cooling fins on the drums. Actually the drums don't need cooling but I wanted strength and they looked good that way.

The next job and the hardest, was the brake plate. The first wheels I made had a welded up unit of tubing that slipped on the axle and had the servo piston brazed on at right angles. I now have a better way. I made a mold

wheel and tire to see what one was like and started to make some more molds. (This put a temporary stop to my own wheel project).

I decided to make one mold for half a wheel and just bolt them together. It sounds simple but it didn't work out that way. I had to melt the first casting out

with an acetylene torch to get it out of the mold. I tapered the sides more and made an arrangement to push the casting out of the mold. I have to watch the cooling close when taking the casting out of the mold. If I do it too soon I distort the casting and if I wait too long I have to warm it up again with the acetylene torch so it

will release. I also found I had to watch the temperature of the metal when I poured it. I found that you just

couldn't get it too hot. (At least in my furnace). I had to 30

JUNE

1960

This is an exploded view of the 5x5 and gives you some idea of the work involved. I make the pistons, push rods and brake adjusting eccentrics and a collar to hold on O ring to keep out dust and dirt.

that holds a piece of % I.D. tubing in place for the servo and casts the whole brake plate in one piece. In the photo you can see what it looks like. I made special jigs to machine the ends of the cylinder to take Willys brake cylinder boots. I use a regular Willys % brake cylinder kit but I made the pistons out of % 24st rod, the push rods are ¥4 cold rolled shafting with a washer brazed on it

to keep the boot in place. The springs I pick up at an automotive supply house. I use a 3/16 screw with a fiber washer to bleed the air out of the cylinder. Next I used % x ¥4 alien set screws with a disc brazed on one end (disc is off center) to adjust the brake shoes when they need it. All you have to do is loosen the lock nut and use an alien wrench to turn them from top to the outside to adjust the brakes then tighten the lock nut again. The brake shoes are

the same alloy as the rest of the wheel and was one of the easiest molds to make. The photo gives a good idea of how they are made. The shoes are anchored on the pivot

This shows an outside view looking toward the fuselage

of the two wheels. The 4x7 is the same on the other side except for the axle hole and valve stem hole. Both wheels are made for IVi" axle.

axle coming out of the other side (the side the cylinder

end by ¥4 in. aircraft bolts which go through a % in.

is on).

enough to anchor the plate to a plate welded on the

the same brake plate on the 4x7 as the 5x5; it saved me a lot of work. I'll try to explain how I mount the 4x7. (The 4x7 is only 4Va in. through at the widest point). First I put on the inside half of the wheel. This half has an outer grease retainer, then the bearing race (pressed in from the inside). Then an inner grease retainer. This completely encloses the bearing and seals it from all dirt and dust. Then I slide on a spacer that goes

bushing on which the shoes pivot. These bolts can be long

axle. The top of the shoes are held together by a spring that holds the shoes against the adjusting eccentrics. The brake plate could also if one wants to, be anchored to the axle by a 5/16 bolt through the axle and the plate between the two brake shoes. Between the inner bearing and brake compartment I use an aluminum plate machined to take an O ring to seal the dirt out. I cast this plate also. On the outside there is a small hub cap which 1 also cast. All in all I think they make a very nice pair of wheels. The local FAA agent said they are as good as any that he has seen. Now to get back to the 4x7 wheels. After getting the local boys fixed up with wheels I got busy on my own

After some experimenting I decided to use exactly

through the inner grease retainer and spaces the bearing from the brake plate. Then I slide on the brake plate and lock it to the axle with the 5/16 bolt that goes through

the brake plate. To do this you have to undo the spring that holds the brake shoes together at the top. Hold the pistons in with a clip while you are doing this otherwise you're going to have a lot of fun putting them in again.

project. I completed the molds and cast some wheel halves

With the shoes folded down it's easy to put in the locking bolt.

different problem. The brakes were inside where they

Next put on the outer spacer which has a hole drilled in it. Position the hole wherever it is most convenient and drill a ¥4 in. hole in the axle and bring the oil line through it. Hook up the oil line, keeping as close to the plate as possible. Next hold the brake drum over the shoes and against the half of wheel on the axle and bleed out all the air and adjust the brakes. (You can get a close enough adjustment this way). There now should be only

and proceeded to machine them. Now I had a completely didn't show. I worried about the heat problem but decided that inasmuch as the brake would have to dissipate the heat through the whole wheel there wouldn't be

enough to bother. I cast the same piece of 5 in. x 1 3/16 tubing as the 5x5 wheels into an aluminum ring which

was clamped between the 2 wheel halves and keyed them together. While on the 5x5 I used 3 one quarter inch bolts to hold them together. I used 3 five-sixteenth bolts on the 4x7. You will notice that on the 4x7 I use one 5/16 bolt to lock the wheel on the axle. In the photo you will see how the bearings and brake plate is mounted. I made a mistake though. The photo should show the

about 9/16 in. of axle left sticking out, past the spacer.

The tire and tube can now be put on by sliding back the

drum long enough to slip the valve stems in the hole.

The wheel halves are numbered so they can't be mixed up. Line up the numbers on the inside half and the brake drum and the outer half. The outer wheel half has the bearing already sealed in behind a grease retainer that slips over the outer spacer. Next slide the outer wheel half on the axle and bolt them together. The

spacers are machined so that when the wheel is bolted together the bearing is under a very slight preload and does not need adjusting. (Caution! Don't mix parts or

spacers from one wheel to the other. They are matched

for each wheel). Both the 4x7 and 5x5 have Timken roller bearings and fit a 1¥4 in. axle. The 4x7 makes a beautiful wheel and is quite streamlined. Nothing shows on the

outside but the bolt ends and the valve stem.

Well, that's all there is to my project wheels. I have had quite a demand for them and if anyone wants any

they will have to give me time to make them. This is a spare, spare, time project, and, oh yes, to come out on

This view shows how the 4x7 mounts on the axle. The photo shows the axle coming out of the wrong side.

them I have to get $100.00 for the 5x5 and $85.00 for the 4x7. (Complete with bearings and brakes). Al's address is: Alfred H. Rosenhan, 830 E. 6400 So., Midvale, Utah. £ SPORT AVIATION

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