Crawler tractors, any published designs?

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Crawler tractors, any published designs?

This topic has 18 replies, 6 voices, and was last updated 7 August 2011 at 18:17 by Alan Suttie.

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3 February 2011 at 20:39 #63491
Alan Suttie
Participant
@alansuttie57682
I’m in the early stages of building a working model in the scale of 1 1/2″ = 1 foot model of a Caterpillar Sixty crawler tractor. The Cat Sixties were built from 1919 (under the name of the Best Sixty by the CL Best Corporation), through the early years of the Caterpillar Tractor Company until the late 1920s. I’m just completing the tracks and am wondering if there were any models described in any publications which used working crawler tracks.

The tracks, because of the high numbers of similar components, became a production engineering exercise. This added interest since I could design and build a lot of jigs, fixtures and special cutting tools to produce the parts on my available machinery. The main shop equipment is conventional, no CNC, and consists of a 10″ swing Atlas engine lathe, a highly modified Myford ML2 turret lathe and a round column import vertical milling machine.

If I can work out how to tack a picture of my tracks on to this post I’ll do so.

Regards,

Alan Suttie
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3 February 2011 at 20:39 #4162
Alan Suttie
Participant
@alansuttie57682
Interested in published details of 1 1/2″ to the foot crawler tracks
3 February 2011 at 21:47 #63493
Jeff Dayman
Participant
@jeffdayman43397
Hi Alan,

I would like to see some pics of your tracks, because if they are similar to the tracks on my next planned model, I might like to buy a set from “Suttie Industries” (if you are interested in selling some)

Thanks JD
3 February 2011 at 22:22 #63498
Mark Foster 1
Participant
@markfoster1
Take a look for Catipillar Sixty 1/5 scale model . in your search engine . Take a look it is an amazing model I think its what you want to build !!!
3 February 2011 at 23:02 #63503
Gray62
Participant
@gray62
Hi Alan, to add pictures, you first need to create a photo album, once you upload your photos, you can then add them to your posts or add a link to them
3 February 2011 at 23:07 #63504
Alan Suttie
Participant
@alansuttie57682
JD:

There’s now a picture of one of the tracks attached to the post. It’s a few days old, since then I have the tensioners fitted and have the carrier rollers and brackets almost ready to bolt on. Sizewise the centre diatance between the sprocket and the front idler is 10 5/8″ unstretched. What piece of tracked equipment are you planning to make?

Alan S
4 February 2011 at 01:36 #63515
Jeff Dayman
Participant
@jeffdayman43397
Hi Alan,

I had a look at your track photo. It’s a magnificent piece of work, well done. Your Cat is going to be a very fine model.

I’m starting preliminary work on sketches and scaling for a steam shovel with tracks. It’s an Erie B steam shovel from USA. I am struggling with whether to build it 1 1/2″ scale or 3″ scale. At 3″ it will do some real work, and would be an easier scale to build working clutches and hoists in, but will be very large to transport and store. These shovels had 3 two-cylinder engines to perform the various functions and so there are a lot of engine parts to make and many gears as well. A daunting model, but I like a challenge.

I have put 3 photos of original builder’s drawings and sales literature showing the track details of this shovel in an album called ‘erie track photos’ which can be accessed by clicking the ‘4 photos” icon under my name at left. They are real heavy duty tracks, LOTS of iron in them.

Unfortunately the shovel’s tracks are quite different in appearance and construction to your Cat’s crawler tracks, so I would not be able to use a set. Oh well, it was worth looking, thanks for sharing your great work.

JD
4 February 2011 at 02:10 #63518
Alan Suttie
Participant
@alansuttie57682
Jeff:

Thanks for your kind words about my tracks, I always start a model with the part(s) which I think will be the most challenging. The sheer numbers of track components was the challenge in the case of the Cat Sixty. The track link sections which form the chain in pairs were the largest group comprising 140 bits (with an allowance for mistakes – of which there were several). Another challenge I’d rather do without is availability of material, I’m in the sticks in Western Canada and I have to make do with local material supplies. Lots of time was spent in prepping sheared plate pieces into a form where I could start “real” machining.

It looks as though you have some decent reference materials at your disposal, the drawing from the parts book can probably be scaled if you haven’t got a full size one to measure up. I got access to two tractors in a museum in California last summer and spent a lot of time with tape measure and camera, so far, however, there have been some dimensions I really should have taken but didn’t.

I managed to get an owner’s manual and two parts manuals for the Cat Sixty as well as some published photographs from caterpillar’s archives.

I’m sticking to smaller scales, apart from anything else I can lift the completed model off the bench. It’s also in keeping with my workshop space and machinery.

Any “castings” are machined from the solid, steel mostly so I can get down to accurate cross sections as opposed to oversize spokes etc. in a weaker material. Over the years I’ve been disappointed in the quality of castings I’ve bought, the usual litany of complaints such as porosity, not cleaning up and inclusions.

Good luck with the Erie shovel – will it be a face shovel with crowding motion and the engine up on the boom and an exhaust at the boom end?

Regards,

Alan Suttie
4 February 2011 at 07:26 #63527
JasonB
Moderator
@jasonb
I’ve seen a nice Holt 45 in model engine builder mag, there are some pics in this thread on HMEM. Slightly different style with teh front steerer.

J
4 February 2011 at 10:47 #63539
Ian S C
Participant
@iansc
Got an engineering friend who’s building a model D-11 CAT, can’t remember the scale, its about 600mm long, and powered by two windscreen wiper motors, I’m sure he’s got too low ratio final drive. Its just chassis and tracks a the moment, and I think the grass grows too quick for it too move too far, the motor shafts turn at 120rpm, into 80:1 90 deg reduction boxes. I’d like to see your tracks, only worry is if he likes them, I might get the job of building a set. Ian S C
4 February 2011 at 13:04 #63548
Jeff Dayman
Participant
@jeffdayman43397
Hi Alan,

Yes the Erie is a face shovel. I am lucky to have 2 full size survivors of these nearby that are operational and the owners have been extremely kind in letting me crawl all over them and measure/photograph everything. One owner has a full set of spares drawings like the one I took the photo of for the track assy. He let me photocopy them which as you say is a great reference for scaling. I was even able to remove a steam chest cover when the engine was cold to examine the very clever reversing valve erie used, when I was having trouble understanding it. Great guys, and very interested in the prospect of seeing a model. As I said these shovels had three two-cyl engines, one engine on the boom for crowding the dipper and shovel as you mention, one for slewing the house and boom and for track drive, and one for operating the cable hoist for lifting the bucket.

Regarding size of model, in 3″ scale the boom would be 57″ long and the tracks about 31″ long end to end over the shoes. The whole model would end up weighing about 1200 lbs, so it would need to move on a trailer behind my truck and have a separate shed built at home to store it. Wife is not too happy with that prospect.

I’m not a fan of castings either, I’ve paid a fortune for some in the past that were rubbish. Now I fab everything from solid. For cylinders and other engine parts I find that meehanite cast iron bar (avail from metal supermarkets here in Ontario) is easy to machine and is very uniform, no blow holes or cold spots. Not too expensive either.

Good luck with your crawler. Be sure to share some photos as you go. Thanks again.

JD
4 February 2011 at 17:41 #63564
Alan Suttie
Participant
@alansuttie57682
I added another picture of the tracks as of yesterday’s progress. The carrier rollers and their brackets are just sitting in position with temporary shafts in place. There are some unfinished brackets in front of the tracks, these brackets were fabricated from mild steel silver soldered in three heats. Finish machining was done once all the hot work was complete, quite awkward to hold for some operations.

The most awkward parts, however, were the 20 U bolts holding the bottom idlers to the channels. They took a lot of tooling to make, particularly the special die to clean up the threads after bending and the chamfering tool to dress the ends of the threads, also after bending.

Regards and thanks for the info from anyone who replied

Alan S
4 February 2011 at 17:56 #63566
JasonB
Moderator
@jasonb
Those tracks certainly look the part

The penny has just dropped, You were obviously aware of the Holt as your DX roller has also graced the pages of MEB. The crawler should be fantastic if your Aveling is anything to go by.

Jason
4 February 2011 at 21:06 #63571
Alan Suttie
Participant
@alansuttie57682
Graham:

I’ve watched several of the video clips of the Italian model of a Cat Sixty. It seems to start and run well enough in all the clips.

Regarding the Holt engine, I’ll be using the Coles Power Models design for the internals only since it doesn’t look like a Caterpillar engine externally. I’ll fabricate the crankcase from steel using a combination of gas welding and silver brazing. In addition to getting external appearance more faithful to the prototype I can get better dimensional accuracy prior to finish machining by taking the individual component parts to near net shape and then welding/ brazing them together.

The smaller components will be machined from solid, either cold finished steel barstock or centrifugally case nodular or grey irons. I’m told the Holt engine is a reliable runner so I won’t mess with the dimensions of the working parts.

Transmission wise, the prototype is easy to copy with the main difficulty being the provision of more mechanical reduction to compensate for a higher crankshaft speed. I have three opportunities for these additional reductions (sounds like a contradiction in terms); the gearbox proper, the right angle drive and the final reduction to the drive sprockets.

Regards,

Alan S
4 February 2011 at 22:32 #63577
Mark Foster 1
Participant
@markfoster1
http://www.blogger.com/profile/00220306033641580497 Have a look at this !!!!
4 February 2011 at 22:36 #63579
Mark Foster 1
Participant
@markfoster1
Here is Lindsay Drabsch and his version Have a look at this !!!! http://www.blogger.com/profile/00220306033641580497
5 February 2011 at 17:55 #63619
Alan Suttie
Participant
@alansuttie57682
Mark:

Thanks for the link, that’s a magnificent piece of workmanship. I found it useful (and heartening) to see that the builder made his transmission housing in exactly the same way as I was proposing to do. That will be my next major component since just about everything on the Cat Sixty tractor hangs on the transmission housing.

Loved the video clip of the tracks being pulled along with a string, that’s a real test of workmanship, I’ll be trying that myself later today once I get the frames drilled for the carrier roller brackets.

Regards,

Alan Suttie
7 February 2011 at 22:32 #63762
Alan Suttie
Participant
@alansuttie57682
In response to those who’ve asked for more pictures I added another one to the album. This one shows the tracks fairly complete with carrier rollers and brackets fitted and the upper dirt guards in place. Only the outer dirt guards are fitted since I’ll need to complete a brace angle which extends from the exposed rear axle under the transmission and connects to the track frames. The inner dirt guards fit over this angle.

The transmission is key to this type of detail so this is what I’m currently working on. The cardboard version is to have a preview of how the final unit will look. I’ve raised the top slightly to get more room for the innards.

Regards,

Alan Suttie
7 August 2011 at 18:17 #73004
Alan Suttie
Participant
@alansuttie57682
Rob:

I just added a couple of pictures to the photo archive. One shows the final drives and the transmission housing with drawbar taken last winter. The second one is from late May and shows the engine block in position on the frames. I was working on the main clutch but came to a halt when I needed to have the flywheel floating in space where it was going to be. This meant that I’d to start the engine crankcase, bearing housings, crank main bearings and crankshaft before I could hand the flywheel off the back of the engine. The prototype main clutch works on a combination of over centre and centrifugal forces. I didn’t think I could get it to work reliably in a smaller scale so I’ve opted to hide a cone clutch inside the flywheel. The actuating mechanism I can make so that it closely resembles the linkgages on the prototype clutch.

There’s a major woops! in the picture with the engine block, one of the dangers of not doing an overall general arrangement drawing. I built the crankcase using a series of sketches and coordinate drilling layouts. Eagle eyed Cat Sixty affictionados will spot that the pushrods are on the wrong side. A little creative machining to the ends of the crankcase and It’s all fixed. Fortunately the crankcase fabrication was almost symmetrical about the centreline between #2 and #3 cylinders.

Regards, Alan Suttie
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