American 35A Loader

American 35A

This was in its day one of VanNatta's biggest and fastest loaders. This American 35A features a pressurized hydraulic system to reduce cavitation. It has power assisted servo controls. There are few logs one is likely to encounter in the Pacific Northwest that it won't handle. This machine which weighs in at around 90,000 lbs is at the upper end of the range of popular sizes for log loaders. We commonly see excavator based machines from the 50,000 lb class to the 100,000 lb class being adapted for log loaders. The logistics of hauling a machine that weighs over 100,000 lbs as well as the expense tends to discourage larger one. The undercarriage on this machine is that of a D7 Cat in the sense that it uses D7 rollers and track chain.

With track pads 3 feet wide it floats better than the Drott 80's, but is less mobile than the rubber tired mounted Drott's. It is generously powered with a Detroit Diesel 6V71T engine. Joystick controls and lots of capacity make log handling effortless. The joysticks operate small servo hydraulics so any function (except the travel which is run with foot pedals) works with the flick of a finger. The grapple rotate and grapple open/close operative with electric thumb switches on the ends of the joysticks. The elevated cab is of particular benefit for logging operations and may be tilted forward to lower the height of the machine for hauling.

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For information on an older version of this same machine configured as an excavator see American 35 as the "A" model is a newer version of the classic '35', where an extensive article appears. The 35A is a somewhat newer model and gets away from the old 'flat pad' tracks that used to be standard on tracked machines, especially shovels and cranes.

No Hook Rolls

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One of the major innovations in the last 25 years and one that separate all of the machinery seen on these pages from a previous generation of equipment is the 'Rotek'. In the bad old days, rotating cranes, shovels and the like all had 'hook rolls'. The rotating structure (the house) was mounted on a thrust bearing in the center. The weight of the house was supported and alignment on the carbody (lower unit) was maintained by this central bearing which, of course, usually had a central driving shaft down through it as well.

The house was then stabilized on this central bearing by Hook rolls. They worked like this. A strong piece of channel iron would be rolled in a circle and welded to the carbody in about as large a diameter as would fit on top of the carbody. Steel wheels would then be attached to the bottom of the house (front and back) which would stick down from the house and then stick into the channel iron so the top and the bottom of the wheel would run inside the channel iron. This steel wheel which 'hooked' into the channel iron took the name of a "hook roll". These hook rolls worked either way, either supporting the weight of the machine, or keeping it from tipping off the carbody, depending on the balance of the house and the load on it. All of these rotating machines have some sort of a counterbalance in the back of them to help offset the weight of the 'front end', but as you might expect, as the load shifts the balance with a hook roll machine the house will tilt a bit as the 'hooks' shift from supporting the weight to holding down. In as much as the machines are usually balanced to be 'tail heavy' when empty to 'nose heavy' when loaded this means that every time you pick up something the house tilts until the hook rolls come up tight. This banging around is a problem because it puts a lot of stress on a few fairly small steel wheels. A broken hook roll can mean disaster as the house can literally fall off the carbody if a hook roll breaks.

The Rotek

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Beginning in the later 1960's a better idea was developed called the "Rotek". I suspect the name is someone's trade mark, but like aspirin, the solution is hardly known by any other name. Anyhow, the Rotek invention is in almost universal use today. It simply consists of a very large ball bearing. Forget the central bearing and the hook rolls. Instead contemplate two large concentric pieces of steel machined so that one just fits inside of the other. The rings can obviously be made of any size, but think of about 4 to 6 feet in diameter for the purposes here. Now take the two rings apart and machine a grove in the respective mating faces large enough to hold half the diameter of a steel ball. Make the grove all the way around both mating faces. Think big about the steel ball size -- Say maybe 2 inches. Now slip the two rings inside one another and drill a hole from the outside in to the grove and stuff the whole thing full of steel balls and plug the hole. With half a steel ball in each ring the rings now won't come apart without breaking all the steel balls or breaking a ring. Now bolt one ring (usually the inside one to the bottom of the house, and the other ring to the carbody. Bingo. You have a ball bearing mount for your machine house and the center of the circle is completely open. This gives you in the middle all the open space you need for rotating valves or what ever you need to pass from the upper unit to the lower unit. If greased reasonably often these Rotek bearings are very reliable, and durable. Pleasantly they have very little slack in them, and the pressure points are distributed among many ball bearings instead of a few wheels. Indeed slack in a Rotek is a sure sign that it needs to be replaced.

Excavators, cranes, shovels, and all types of rotating machinery today uses these Rotek bearings. The concept is very scalable and can be sized to any application. Though no one wants to be without them, they are relatively expensive, and their replacement is sufficiently difficult (you have to unbolt the house and lift it off the carbody) that a Rotek failure is often the driving force of a decision to scrap a machine.

American abandoned the excavator market in the early 1980's as did most domestic manufacturer's. Their success is still around making heavy lift cranes, but alas, this machine is an orphan, and an increasingly rare orphan at that. No one wants to use this machine when given a choice of it or the next generation electric piloted high pressure machines such as the Link-belt 4300 featured elsewhere on this site. We were very proud of this machine for a long time, but the pride continued for about 48 hours after we became the owners of a next generation machine.


Featured here is an American 35A hydraulic logloader loading a mule train trailer. This particular model features a D-7 Cat Undercarriage, and a 6V-71T Detroit Diesel for power. It features lifting capacity for the largest logs and an extremely long reach. In its younger years, the carbody featured adjustable width tracks which could be widened for stability or narrowed for transport, but alas, the tracks are now permanently in the wide position with about a 10 foot gauge, (width measured to the center of the track). With a pad width of 3 feet the overall width is about 13 feet, a manageable width for logging equipment, but also an ample explanation of why we are building sideboards for the 10 foot wide lowboy. It is somehow spooky, even for a logger, to drive a critter like this up on a lowboy with precisely half the track pad width hanging out on each side. It is doubly complicated if you load over the side of the trailer and then plan on rotating the machine 90 degrees while on the trailer.

Dateline 2003

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American 35A Excavator
Well, this puppy had its day as a log loader. IT served us well for a decade or more, but then we bought some Link Belt 4300's which are a newer generation shovel (loggers call their loaders shovels) with electric over hydraulic controls. Once we got our hands on those controls this puppy got parked. The electric controls are modulated, so if you need to move the boom an inch you can do it. The piloted hydraulic controls pretty much have two positions--on and off- making the loader seem 'clutsy' by comparison. For example the time to load a dumpster box with pulp wood scraps was reduced by about half with the new generation machine.

With this mighty machine sidelined as a log loader, the logical thing to do with it was to refit it as an excavator and stick it in a rock quarry to load rock trucks. Loggers have been doing this with old shovels for as long as shovels have existed. One of the reasons we bought the American 35 years back was that it had an excavator front that would fit this machine. In the mean time it has been sitting in the quarry doing what excavators do in quarries, but the tracks were so bad that they were breaking and the cab was about to fall off so we decided it was time for an upgrade, as this machine had a nearly new undercarriage of the dozer type.

The swing gear was leaking grease but we were able to resolve that issue on the cheap side. Upon removing the swing gear assembly we discovered that the bottom bearing was loose because the last guy hadn't quite figured out how to set the locks to hold the bearing in place. We unraveled that mystery and put a new seal in and that problem was solved. Pulling the swing gear isn't the biggest deal in town if you have a suitable service truck. You have to disconnect some hoses and move some plumbing, and then it is pretty straightforward. The swing gear is bolted to the deck with several bolts which are addressable with a big impact wrench and a lot of extensions. then you have to back off some set screws that adjust the backlash in the gears and hold the swing gear laterally. Once this is done a nylon strap and a skyhook that will lift half a ton and you are in business.

I removed the logging front mostly with the service truck. I took it apart a piece at a time starting with the grapple, then the heel rack followed by the dipper, and of course the cylinders as I went. Getting the boom off was a little more dicey. I used a front end loader to hold up the end of the boom while I harvested the boom cylinders. Then I set the boom on the ground. We then brought another log loader into position and bridled the boom just outwards from the point of balance--the goal being to lift about 90% of the boom weight and lifted the boom off the ground. We then knocked the boom base pins out and swung the boom out of the way. In doing this it is important to remember a few things. First, the house will want to swing until the counter weight is down hill if you are off level. Secondly, while you want to choke up on the boom near the center of balance, you don't want to over do it or the back end of the boom will pitch up in your face when you knock the pins out (not a good thing).

As for the excavator front, we were moving it from one machine to another so I decided I would move it as a whole assemble without dismantling it. What I did was dig a hole about 15 feet deep and put the arm and the bucket down in the hole. We layed a log on the ground just behind the hole and layed the boom on it. With the whole arm and bucket down in a hole and the front of the boom laying on a log the otherwise awkward assembly couldn't very well fall over on us. We then brought another log loader in position to lift the back of the boom, and drove the pins out, sealed off the hydraulic ports and drove the old machine out of the way and the newer machine into position, and reinstalled the pins and were on our way.

Actually the bigger job was dealing with the elevated cab. To work as a log loader, the cab and been elevated 4 feet by simply removing the cab and inserting a 4 foot spacer under it and bolting it down again. I reversed the process. Since the controls were mostly piloted hydraulics I just had a bunch of lines that were too long---but they had been spliced when the cab was elevated so I managed that by removing the splices. The wiring harness was toast anyway, so we rewired it. A log loader requires a couple more spools than an excavator does (for the grapple open/close and grapple rotate). We removed one of the circuits and kept the other to control a thumb we are adding to the excavator front. The elevated cab isn't a bad thing for an excavator except for the Tarzan exit and entry. You don't need the elevation to see what you are doing and climbing around gets old, particularly when you get old as well. This machine should live quite a few year in a rock quarry loading rock trucks from time to time.

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