The Allmand Drive System

 It all started here, this is an old page, and I leave it here as a record of our early efforts, please see the pulley page for what's happening today.


    NOTE, These pulleys are made to work with easy to find automotive serpentine belts, not expensive industrial belts, you can expect thousands of hours of service from one belt, and far greater efficiency. There is a major difference in cranking effort between a Vee belt and a serpentine, and you will be making a noticeable amount more KWHs from the fuel you burn.

Because this is a 'bushed' pulley, you can quickly and easily move it from one size shaft to another. Since this is an SK bushing, it covers a wider range of shaft sizes, as you never know what you might want to try tomorrow. 

did you stumble onto something cheaper? Does it have the more flexible SK bushing? Is it really the right size for your application? Need a different pulley? Trade in your present Allmand pulley for a different size anytime. You never get stuck with the wrong pulley.

 Let us know whether you have a 22.5" or a 23.5" flywheel, and we'll do our best to match the pulley more closely to your individual needs. We stock a pulley for 22.5 and 23.5 wheels. snap a tape measure around your wheel, and give us the circumference when you order.

email me with your requirements or questions.

 Added Note 01/30/05, Before we invested in making Custom Pulleys, we did our research. I contacted Steve Gray at oldengineshed.com and learned that the old engine crowd has been using the auto serpentine belts for many years, and they (Old Engine Buffs), were pleased with the results. Before we tooled up, I researched sheaves to the full extent, and there were none a DIYer could afford that offers what we build for the money. There were a few folks running hardware store consumer type heads with a retrofit auto pulley (3600 RPM heads), but we were after something slower.   We looked at off the shelf (8.x") stuff and found high prices or other issues that got us too far away from KISS principle.  

   As of 2004, there are a number of off grid sites running this drive system up to 16 hours a day on Listeroids. We even know about one guy in Colorado who bought a pulley, and ran it for 1500 hours, and decided to offer this The drive is designed to use one of the strongest belts available to date, and one of the easiest belts to find locally. For those on a tight budget, you're likely to find a replacement in the nearest scraped auto. This design offers reliability, and high efficiency. It is also cheaper than buying two quality pulleys, the proper bushings and a high quality Vee belt. The Allmand System also allows the engine and generator to set inline with each other versus a major offset to accommodate pulleys fitted to the engine crank shaft, (remember that gib key sticks out a ways, and forces you to mount further outboard). The Allmand Drive reduces the footprint significantly. In Addition, it makes it easy to build the generator set. In the case of the 6/1; it's wise to avoid Vee pulley systems if you are interested in efficiency, get more energy to the gen head, and you get more Kilowatt Hours of electricity per gallon of fuel. Some people who see this drive for the first time want to know if the belt ever slips on the flywheel? The answer is no, the surface area is far too great to allow slippage. The custom Allmand pulley acts as the pilot and the belt tracks perfectly straight. The pulley is  heavy, and well machined, very little tension is required to keep the belt from slipping even when overloaded. All that you need to do is build a proper mount for the engine and gen head, I provide all the info necessary to accomplish this. If you have ANY trouble Setting up the Allmand drive, you are most likely mechanically challenged to the point you should not be around machinery of any sort anyways. 

 I found there are a number of  Industrial 'Micro Vee' (serpentine) belts/pulleys in use, most all pulleys I found were too small for a good match between prime mover and gen set. The other disadvantage was becoming dependent on an industrial supplier, and the high prices for Industrial belts/pulleys. The price difference between the industrial belt and the Automotive belt can be significant. If someone takes your belt, or you figure out how to mess it up, you could be down for a while, Murphy will make sure it's at the worst possible time. As I mention elsewhere, the Automotive belt is everywhere, and you'll be able to find spares 25 years from now because they keep using this size on a good many new autos. Yesterday I got a very nice take off from a repair shop for free, it came off a mid 90s Ford explorer, and it's now used on a Lisgen_6/1_ ST3... perfect  fit! Think of the future, this is a long term Investment, don't leave your Grand Children a problem sourcing a belt. There is no better pulley material than cast iron, there is no better choice in belts than the automotive serpentine belt. I received an email from a guy who is using a 6 Rib serpentine on a 15KW head and says it's working fine,  I would personally move up to the 8 Rib, and keep the pulleys large, that's key in transferring higher torque. 

Allmand Drives allow the slow speed Listers (and other old open flywheel engines) to drive the 1800 RPM generator heads directly off the flywheel.. These pulleys are nice enough to hang on the wall.... and more important, they work great.

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Above left is an inspirational picture of an old Lister light plant.  Above right is the Listeroid fitted with the massive 5KW/ST  generator head.

Inserted Note: As of 6/2003, I have built a number of Listeroid gen plants that use this drive system, and I have a good number of customers/friends that are using them as well.  Take a look at Steve Gray's beautiful Lister generator. Steve's set up has made two big shows this year and draws a crowd. The ST head is the proper vintage to go well with the Lister.  Readers might ask why Steve didn't go with some old flat belt system?  I didn't really pin him down on that, but my research led me to believe it would be expensive and less reliable.  Steve did tell me that the old engine crowd uses serpentines all the time.  There's also a thin slice of Survivalist that runs through me that constantly reminds me of the advantages of the KISS principle and the rewards of using common components you can buy anywhere. The serpentine belt I use for the 6/1 is 'typically' 91-92 inches long and is found in many years of Ford/Chevy V8s and V6s. Look under the hood and add up all the loads placed on that single belt! Air conditioning, power steering, Alternator, Water pump, and sometimes more. After the fourth time I was told my serpentine belt looked real bad on my Chevy pickup, I bought a spare and put it under the driver's seat.  I drove it for a few more years. After 12 plus years on the same belt, I was shamed into changing it,  it was the wrong thing to do....I should have gone for the world's record...

If you're in the middle of nowhere, and you figure out how to tear up this belt, (let me know how you did it) a spare may be found in that upside down Chevy at the local bone yard. And if you're feeling like parting with a whole twenty some dollars, NAPA, or a host of other automotive suppliers will have just the one you're looking for brand new. The price of Automotive belts 'usually' has to do with the volume moved, this size is a big mover, and is 'usually' cheaper by far than a shorter or longer one. 

This is only half the story, the reason the Automotive world went to the serpentine belt was not to save you money on belt changes, it was a matter of efficiency, this system transfers energy from the prime mover to the loads with less loss resulting in better fuel economy, which gave them the ability to lower gas mileage averages and increase their offerings to the public and still stay within the Federal guidelines. It was good for them, that's why they did it!

After an exhausting search for a proper sized serpentine pulley to drive the 1800 RPM load, I decided it was time to invest in making it versus spend more time looking for it. You can only stand to wait so long.

Machinist Randy Allmand made himself and his machine shop available for prototyping the pulleys. Randy is a respected Hot Rodder and Fabricator, and has done lots of machine work for racers including the unlimited Hydro plane crowd.  His personal lawn mower would make the 'tool man' jealous.

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Here's Randy.....If it doesn't look right, it doesn't get out of his shop......

When you're doing one off stuff, it takes time, an no matter how simple the part looks, it isn't (IMHO).

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First frame, steps are taken to assure close tolerance, 2nd frame, setup to assure accurate taper to receive the standard SK style bushing. 3rd, SK bushing is test fit to assure proper engagement and depth.

If you have no experience with 'bushed' pulleys or sheaves, the bushing can be ordered for the shaft diameter you are using. This means you can mount this pulley on any sized shaft that you can get the bushing in, or bore it to your own size. Metric sizes like 32mm, 38mm, 42mm, 48mm, are readily available through vendors. Get the bushing mailed directly to you by calling Applied Industrial. Simply ask for an 'SK' style bushing in the size you need for your generator shaft. 

Inserted Note: It's KISS again, you can't get more common than the SK bushing, it allows you to move your pulley from one shaft size to another. If your pulley (Sheave) experience is limited to fractional horsepower stuff, or lawn mowers, you'll be amazed how the bushing locks the pulley in position and how you can can move the three bolts from the locking position to the 'jacking' position and back the bushing from the matching tapered bore in the pulley, one small wrench is all that's required, even Girls can do it :-)

Unlike the junk you find on consumer riding lawn mowers, bushed pulleys are what serious real time reliable products use. If you've ever seen a shaft all torn up when some cheap pulley came lose, you'll never invest in anything other than a bushed pulley. When a pulley fails on the lawn mower, it's time for a beer, when it fails on the generator, a beer is the last thing you'll be thinking about, and if your married, you will NEVER be allowed to FORGET it.............are you listening Steve?

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Here's the result of a day in the machine shop. That raised part in the center is a standard SK bushing.

This particular picture does not show off the fine machine work of this pulley. The Micro Vees have been cut with a precision machine tool. The pulley shown is set up for the more common 6 rib belt. This belt is less expensive and will do a fine job with the 6/1 Listeroid.  If you want more,  we build a limited number of 8 groove pulleys. Note the relationship between the gen head and the flywheel, keeping it short coupled is a good thing. 

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As we know,  belts like proper tension. This threaded rod passes through the end of the generator frame where spring pressure can be adjusted and tension maintained. (Note added 4/2003), some folks are running without a tensioning device, and report it is working well for them.

July 14, 2002

Today we prepared the Listeroid 6/1 ST Generator for belt drive testing; when it first fired up, the belt was squeaking some, I applied a little tension and things got quiet and smooth.  I placed a 100 watt Vapor light on the generator for a load, the engine's grandfather clock sound didn't change. The serpentine belt runs exactly dead true on the flywheel.

I stopped to recall how pleased John Culp is with his 6/1 serpentine drive, in his case, the pulley on the generator is a mere 4 inches in diameter and has carried 4600 watts!  Our large diameter pulley has several times the area under the belt and should NEVER slip even with the fuel rack all the way open.

I took my two horse power chop saw down and put some hard wood under it, I pushed the blade into the wood and started it stalled. Those big ole flywheels are magic; it took a bit for the exhaust note to change, but the speed of that flywheel wants to remain constant. There is no better frequency and voltage control than a big ole flywheel and flyweight governor, an electronic device can't make up for a lack of flywheel mass which stores energy and smoothes out transitions in load. If you research old light plants, you will see that flywheel mass was often increased when the engine was deployed as a light plant.  

I am totally pleased with the serpentine drive system, this pulley is everything I hoped it would be and then some. Not only does it run true and grip well, it adds character to the gen set and looks like a well made, machined piece from the past.   If you choose to drive off the crank, you are much further out on the crank. This lever effect increases the side load on your main bearing and will greatly increase the width of your gen set with the requirement to off set the head. 

Another noteworthy advantage, when you attempt to start a Lister with a Vee Belt drive, you can feel the drag of the Vee belts, and it makes it harder to start. The difference between the Allmand setup, and the typical V belt system is very noticeable. I think the serpentine could allow the slightly built people of the household (girls :-)) to start the set manually, where they may not be successful otherwise. add some cold weather, thicker oil, and even the Governor, (Arnold S) would appreciate the Allmand Drive.  




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Above is a picture of the Listeroid 12/2 fitted with a 10KW ST Head. 

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Above is the 2002 batch of custom serpentine pulleys designed for the stock SK bushing. Note the Listeroid green color, it's a reserved, unpretentious color, and fits the character of a slow speed Listeroid perfectly, check out "Dark Hunter Green in a spray can"  Look at the picture above this one to see the pulley mounted with the SK bushing in place.

As of 6/04, we are making 3 different pulleys

Six groove for the 650RPM 6/1s

Eight groove for the 650 12/2s

Eight groove 11.1 inch 25 pound pulley for the 1000 RPM singles and twins.


Above: Here's the huge 25 pound 11.1 inch pulley designed for the higher speed singles and twins with the big flywheels. There are some 25/2s being built in India that run at 1000 RPMs, this pulley, and the 8 Rib belt should carry a 15KW head, it'll eliminate a good portion of frictional losses and make for a much smaller foot print. You will convert more of your fuel into Kilowatt hours, this is good for your pocket book, and good for the planet. Note that the gib key forces you to place any drive pulley some distance out from the flywheel, this increases the side thrust on your bearings. We can say it's not a big deal, but for the long haul, less is always best, and the further out we go on that shaft the more we aggravate the problem.   

It has taken more than a year of research to figure out how to make a pulley of this size where regular people could afford it. I was able to locate some ready made industrial pulleys near this size, but they were in excess of $450, and Allmand is better!  To the left is the Allmand 8 Vee 8.250 inc pulley, this new 11.1 pulley certainly dwarfs it.

A note on the large pulley: If you start looking at the massive circumference, you'll not be surprised to know that machine time triples. there is also a need to invest in more expensive tooling to get cost effective tool life for the longer cuts. The greater radius demands greater attention to detail, and craftsmanship that is probably unheard of in India. The big pulley above tracks like the custom part is is...there's no wobble, and no run out. Yes.. you could get by with less investment in the machine work, but Randy only has one mode he runs in, and if you want a lesser part, you have to go elsewhere to get it made. The precision helps convert your investment in BTUs into more Kilowatt hours, if that's not a concern, save yourself a bunch of time, and go to the hardware store for an off the shelf gen set.     

There are some 25/2s being built in India that run at 1000 RPMs, this big serpentine pulley, and the 8 Rib belt should carry a 15KW head.

Above is a temporary setup in Costa Rica, even if the pulley were set further in on the crankshaft, and  the head were turned around, the foot print would be considerably larger than an Allmand drive, the frictional losses are greater, and the small pulley on the gen head (above) has so little contact area that slippage at full load is almost assured. Note the real nice cooling system, and the custom rack! The owner of this Gen Set is working on improvements.

The picture above makes an excellent example of an important aspect of sizing pulleys and understanding them. If you think in terms of a lever, and you study the radius of a pulley, it is no different than the length of a lever. The wider the pulley, the longer the lever. I would guess the pulley diameter on the above gen set is little more than two inches. Consider that the belt has little surface contact with the belt, and it also has very little leverage because the radius is so tiny. there is a third factor working against us, the belt is forced to make a very tight turn around this pulley and the belting is worked further creating even more losses.

I have had a few people look at the Allmand system and comment on the small belt, some of us catch the fact that the pulley used has a HUGE diameter compared to the little 2 inch pulley often found on the auto generator, the mechanical advantage with the Allmand drive is HUGE. If you  couple two devices together using 2 inch pulleys on each shaft, the ratio is 1:1, if you coupled the same devices together with 10 inch pulleys, the ratio is still 1:1. The difference? With the smaller pulleys, there is a need for the belt to handle far more torque, but it's speed is much lower. In the case of the big pulleys, the belt travels at a much higher speed, but carries a fraction of the torque. Serpentines can handle the speed, and they are quite strong. What you need to remember is the actual torque they must carry has a DIRECT relationship to the pulley diameter they will be used on.. Lots of folks buy small pulleys, and they cause nothing but trouble in a good many applications. 

Above: This is the latest Allmand creation, 8.260 to 8.620 effective size. IMHO, this is the perfect pulley for a 6/1 and 1800 RPM gen heads. I would have no problem using this on the 12/2 with the 7.5KW ST head as well. I will do my best to keep this model in stock at all times. Keep in Mind, this pulley is SK bushed, it does NOT use the smaller QD that limits you to smaller shafting.

We can make custom six groove pulleys from 8.260" to 8.600", custom 8 groove pulleys from 7.8 to 8.3, and 10.9" to 11.380 inches. Some sizes will take more lead time, 8.3 six groove are normally stocked, other sizes are harder to stock.

Use the following to discover how a particular pulley size will perform on your Generator set.

Here's some things you may find helpful.

ALWAYS use a small tape to measure the circumference of a flywheel then divide this amount by Pi to get the diameter, this is usually far more accurate that shooting around the shaft. 

There's a spread sheet on the utterpower CD you can use to explore pulley ratios, but here are the simple formulas you'll need.

A= Engine Flywheel Diameter, B= Engine RPM, C= Generator Pulley Diameter, D= generator RPM, E= Frequency

A= C*D/B,  B=C*D/A,  C=A*B/D,  D=A*B/C, E=D/30 (ST 4 pole heads)

Auxiliary uses for the bushed cast iron serpentine pulleys

Above: Hmmm, how about driving an auto air conditioner for off grid use? Maybe it would make a great compressor for a fridge? Since they're set up with an electric clutch, you could cancel the load.

Here's how to make your own generator using the Lister 6/1 and the ST head.


George B.