A Tandem Cub
 

I thought I'd start a thread on a new project, a tandem cub. I'm thinking it will eventually have a cargo bed behind the seat. It's intended to have two driving axles with a pair of hydro drives coupled together. At this point, I'm considering this a proof of concept effort. Below are my current ideas and thoughts.

It's a 109 with an additional axle out of a 147. Frame has been extended and reinforced. Something of a jerry-rigged frame made from the rear portion of the 147's frame plus some steel stock I had on hand.

The plan is to connect both sets of brakes so both rear axles have working brakes. The hydros will be linked with a rod from the front control plate to the rear plate, making them move in sync, or close to it.

The 109 was running when I bought it, albeit with fuel supply issues. The PTO had fallen off, bearing disintegrated. Engine did not smoke, so a carb rebuild will get it running enough to allow me to test the drive train. If it all works out, I will probably drop a newly rebuilt engine in it. I have one waiting on the shelf.

I intend to cover both sets of wheels with extended fenders, perhaps a combination of the 109's and the 147's fender assemblies, cut apart and welded back together in some fashion. I may put a wide seat on it so two people can sit side-by-side, like a golf cart seat perhaps. Not sure yet.

I did buy four new 23x8.50x12 Deestone ags and have cleaned and painted 4 wheels. So those will be going on shortly. Axles are 24 inches O.C. so that leaves about an inch between the tires.

The front hydro (the 109's) has been drained and refilled with a new filter. Rear (the 147's) hydro is awaiting a replacement suction tube then will get a fluid and filter change. The 109's trunnion is worn a little, and the 147's is in better shape. The jump shaft (from the front to the rear hydro) is just loosely sitting in place in these pictures.

Once I get it running, and have some confidence that it will work as intended, then I'll clean it up better and deal with the cosmetics. No sense getting all fussy about it if I wind up scrapping it in the end.

Open to any suggestions or ideas you might have. Have several other projects in progress around the house, so this may take all winter.

Looks interesting. Bound to be a lot of folks to tell you it won't work, that's just the way forums are. Are both rear ends geared the same? I'm asking here, because I have no idea if they all had the same gear setup. You mention brakes on both axles, I'm thinking individual turning brakes would be better, It's bound to be a little hard to turn.
So, is this for around the house, or are you going to haul firewood out of the woods, run around muddy pastures, etc.

Got my popcorn ready! Hope this build works well for you!

:popcorn::popcorn::popcorn::popcorn::popcorn:

Cool project. I would put a ported pump on it to make the bed hydraulic dump.

I assumed that hydros were all geared the same. No? Same output shaft... I know that the gear drives were not.

turning brakes is a good idea. I'll find out how difficult it is to turn then decide.

Planned use is around the house, taking gear/luggage/provisions down the hill to the dock and boat, and back up to the house, etc.

Really, it's just something to tinker with.

Yeah, I thought about that but don't have a spare ported pump. If this works, then I might consider buying and swapping out one of the hydrostats. I did look at a possible hydro pump running off the front PTO or even a Cub hydro pump, but that would likely be cost prohibitive...

Looks great to me!! Sometimes the best way to figure out if something works or not is just to try it!!:beerchug::beerchug:

I'm pretty sure all the hydro garden tractors had the same gearing.. the supers were different.. somebody correct me if I'm wrong!:bigthink:

Keep us posted!!

I would think the rears were the same as well, but to be sure, I checked the parts book. Checked 3 gears/pinions and each machine list the same part numbers. I checked the part number for the pump itself and that is the same--for tractors without hydraulic lift. I would assume a ported pump is the same, other than the ports. Wouldn't hurt to verify that before you start thinking hydraulics---I think that is a fabulous idea of adding a dump bed. If hydraulics don't pan out, a lot of utility vehicles use electric lifts.

Pretty cool project. You are bound to have some problems as you go along but work thru them and you'll have a finished tandem dump you're proud of. Keep us posted with pics of your progress.

Looking forward to seeing your progress on this...:popcorn:

May as well put growser tracks on it while you are at it.

:IH Trusted Hand:

Try to get the two rear axles as close together as you can. Farther apart they are the harder it will be to turn. Picture turning a corner and the rear axle having the best traction, the middle axle would literally have to be drug sideways. Closer would ease that a little.
Cool project, good luck.:beerchug:

The axles are literally as close together as tire diameter will allow. I put a pair of turf tires and wheels on one side the other day, and there was about an inch between the two tires.

Sorry must be an illusion to me looking at those pics. Keep up the good work!

Seems someone was trying this earlier in the year.:bigthink: Don't think it was ever finished after some of the issues were pointed out.
One I remember was the rear axles. Without them floating, traction was an issue on even the smallest of hills. In any uneven terrain, the forward, or rear axle would come off the ground...
Pretty cool thought, I'll be watching to see what you end up with.:beerchug:

Found it.http://www.onlycubcadets.net/forum/s...ht=tandem+axle

Yeah, I was in on that discussion. Very similar builds (and build on the fly approach!) Never did get an update from that thread's OP, did we?

I thought about a suspension system for the rear axles, and had developed a preliminary design, but the cost of the components just got out of hand. I can always go back to that within this build if I get ambitious.

It might help terrain following if there was a hollow trunnion in between the rear axles.
The hollow would be for the hydro shaft to run through.

Probably would make even harder to turn, LOL.

Sure, you may have traction issues, but since this is just a fun build as part of your hobby, weld it up as you go and see how it turns out. If, when you think you're done and the traction is an issue, cut it up and try again. Just make sure to post some pictures!

Best reply yet! Now get busy in the shop.:popcorn::popcorn:

I have been busy in the shop today! Waiting on cabinet parts to finish the wet bar in the basement family room, so I got a reprieve from the "home" work.

Here are some pics. Added the front to rear brake links with turnbuckles to adjust the rear brakes independently. I may yet go back and join the original existing front and rear brake rods, as it it turns out they are beefier. Not sure my 1/4 inch rods will hold up.

Installed the jump shaft (front to rear hydros).

Replaced the damaged suction line on the rear hydro. The PO had a hose clamp over the damaged spot. Got a replacement off ebay. replaced the filter and fluid in the rear axle.

Replaced the manual relief valves with auto valves.

Primed and painted the frame to prevent rust.

Finally, hooked up a drill to the drive line and tested operation briefly.

Have not linked the front and rear hydro control plates yet. That's next.

Also need to get my four new tires mounted. I tried to mount one of them today but my HF mini-tire changer (used to mount a bunch of tires before, including 4 pair of Tru Power ags) couldn't get the the first 6 ply deestone ag on the rim. Taking them to a local shop on Monday. Not worth wrestling with any more.

link to drill driven drivetrain test: https://youtu.be/CR4mgLJFy7Y

Looking good!!:beerchug: You got a lot done today!! Keep us posted!!

We had a tandem grain truck once that didn't have equalizers between the front and rear springs.. It worked great on the pavement or hard level dirt.. but we did have traction issues in the field or un level ground. But the rear axle was just a tag axle.. wasn't powered..

I'm interested to see how she works out.. I'm pulling for you... I hope and think it will work with power to the rear axle..:beerchug::beerchug:

Keep the pics coming!!:beerchug:

Got my tires mounted today. I was disappointed that I could not mount them with my HF mini tire changer, but after taking them to the auto shop, where even they complained about how stiff they were, I don't feel so lame. And they had an automotive tire machine. Cost $48.00 and tax to have four tires mounted with tubes installed. Sometimes it makes sense to through in the towel, so to speak, and pay the pro.

I mounted a couple tires on one side just to check tire clearances. I was sweating this a little, as I put the two axles 24 inches on center, and assumed I'd have an inch between tires. I checked it out with a pair of turf tires, but wasn't sure how the ags would work out. Luckily, it all worked out. See pics.

I'm now working on linking the two hydro controls. I plan to run a rod from the front trunnion control plate to the rear plate, with the ability to adjust the length so I can sync the two hydros. I don't expect to be able to get it exact but it should be close enough.

Just a note about the brake linkage I installed. Did you know that the little brake actuator links (that pivot to compress the brake pads) are hardened? And that even a cobalt twist drill will just skid off? And that a center punch makes almost no dimple? I had to pull out the carbide twist drill to drill the holes. I got through three of the links, using cutting fluid, before the bit got dull. Sharpened it on the diamond grinder wheel I use for carbide lathe bits.

I only mention this as I expect the hydro control plates to be similar heat treated material. Haven't tried to drill them yet, but my plan is to drill both plates to link them so they move in tandem.

One final note. I put 23x8.50 tires on this build because I had 4 extra 7 inch rims and zero 8 (or is it 8.5?) inch rims. If I had the larger rims, I'd have put 23x10.50 tires on this. FYI, the four deestone 6 ply tires cost $199 shipped from an ebay seller. I normally go to Miller Tire, but didn't see them on their site.

Looks good so far. Yeah the plates on the side of the hydros are hardenend. We wanted to bend the one my 2072 so it would line up better with the springs. It didn't bend, just went SNAP!:bash2: And that was with pry bars while it was still in the machine.:bigeyes:

coming together fast!
So.............what is the planned use for the hydro drive shaft output to the rear of machine?

That shaft was temporary so I could drive the hydros with a drill for testing purposes. If you look at the youtube video I linked to in post #20, you'll see the drill driving the hydros.

Though, I was looking today at mounting a small hydraulic pump to drive a dump bed cylinder. This one is about 3 inches square, 4000 max rpm, 2 gpm at 3000 psi. https://www.northerntool.com/shop/to...9714_200329714

Cheaper to get a ported hydro pump. Easier to hook up to also. Could even use the 1X8 series hydraulics. I'd buy a ported hydro pump and a cylinder from Surplus Center.

Nice job so far Frank! :beerchug:

That's coming along very nicely. If you do decide to mount a pump off the rear for the dump bed, be sure to have enough capacity in your hydraulic reservoir to help cool the oil. Having the pump turning constantly will create some added heat. Keep the pictures coming!

While that is a good point, that pump is smaller than the charge pump on the hydro, which runs all the time.

Another note about using a ported pump is the hydro's do help cool the oil. Whether using a seperate pump, or a hydro, one or both rears can still be sued as a reservoir.

OK, some more progress, and obligatory pics.

I cleaned up the frame, did some sanding, and put some color on the rest of the frame. Rattle can paint. Mostly so it would all be the same shade of yellow. The rest of the painting will probably wait until after I've had a chance to do a test drive.

Mounted the remaining (port side) wheels and removed the jack stands.

Spent the next couple hours drilling the control plates and creating the adjustable link between the two plates. It's important that the attachment points at the two plates be at the same distance from the shaft so both points move the same amount as the lever is moved. If one attachment point were to be further away from the central point of rotation, it would move further than the other point and the two plates would not move in sync.

Drilling the plates was a chore. Again, had to resort to a solid carbide twist drill bit. Thank goodness for McMaster Carr. Also, in case you are interested I had to buy a LH die to thread the link rods. I had the standard (RH) taps and dies, but you need a LH die as well if you are using a turnbuckle. McMaster Carr is a great resource (mcmaster.com). Stuff I order arrives in less than 48 hours.

If you decide to buy a solid carbide twist drill bit, you might as well buy a couple. They are very brittle and easily broken. I've used them to drill out stubborn spirol pins. Use them carefully, if they snag in the hole, they will likely break off. Then you're in a pickle. A carbide bit (or any drill bit really) broken off in a hole is a problem for sure.

I have some reservations about the rod and turnbuckle hydro linkage. I used them for the brakes, but those are always in tension. A rod and turnbuckle arrangement is not the best arrangement in compression. I'm unsure about the level of stress that will be placed on this hydro linkage. I thought about using a flat piece of steel, 1/8 by 3/4, long enough to connect the two plates. But I need to be able to adjust the length so the two hydros can be synchronized, specifically in neutral. A pair of flat plates with slots and bolts would allow some length adjustment. Alternately, I may take the spare hydro control rod that came out of the 147 (5/16 rod I think) and cut it and weld in a new section to make it longer. This rod has the ball joint linkage at each end, with some room for length adjustment. I didn't want to do that because I didn't want any play in the linkage and the ball ends have a bit of play. So we will see how this works.

Next up is to clean the carb and get this engine running again. As I mentioned, I have another engine (10 or 12 hp, don't remember which right now) that I can drop in.

Thinking ahead, I will need to temporarily mount some sort of seat to test this thing out once I get the engine running.

maybe an alternative adjustable hydro synclink could be like a tierod.
Tubular steel tube internally threaded LH and RH with male NF yoke ends?
The tubing would be much stronger pushing than the rod or the flat stock.

Jon - never gave a thought to using the hydros as a reservoir. Good call. Tap in a suction on the drain plug and put a return in the top cover. Easy peasy. AND there's all ready a cooling fan!

Make a solid control rod with tie rod/ or ball socket joints on each end, just like the original linkage from the swashplate to the handle lever. Tie rods were used on it, and are fine. They only have play when they are worn out. You can thread the rod LH on one end, and RH on the other, so it would be adjustable. Use jam nuts. If you don't like the tie rod style, use a ball socket style.

:IH Trusted Hand:

I have the ball socket style rod from the 147's linkage (lever to control plate). That's what I was thinking about lengthening. The rod that connects the clutch/brake rock shaft to the (not sure the correct term) the neutral/brake plate has a clevis end with a threaded section. Either would work.

I'll leave it as is until I get it running and see how it works.

I agree 100% that a ported pump is the best way to go, and for sure would be less expensive. I won't make any decision until this thing is running and I'm convinced it will work as expected.

Decided to go with Jon's and Double07's recommendations to upgrade the hydro sync link.

Used the 147's (donor parts tractor) hydro control rod and substituted the clevis from the brake/neutral rod for one end. Added some additional 5/16 rod in the middle (to preserve the LH/RH threads already on the donor rod) and reinstalled the new rod.

Working on the carb today. (taking a break for some lunch right now).

I'm anxious to get this build outside so I can wash some of the grime from the forward hydro, frame and engine. I should have done that before I brought it into the shop.

Looking at the dirty engine while I was rebuilding the carb, I made the bold decision to pull it and put in the rebuilt K301 I have that's been on the shelf since last year. Moved it from the garage to the shop with the orange tractor.

Alvy, if you are listening, I think this is the engine with the crank I got from you.

Both of our GSDs, Brutus (blue collar) and Butchie (red collar) are constantly "helping" me. For example, today I found several box end wrenches in the yard. I guess they felt they needed some air or sun or whatever. Can't leave anything on the floor when I'm done working!

So I cleaned up the frame a little, spent some time adjusting the steering gear box since is was easily accessible, and set the K301 in place.

The K241 I removed has a damaged keyway on the crank where the starter pulley/PTO basket was loose for some time. So I'll have to decide what to do about that later.

Oh yeah buddy loud and clear. I’m really liking your project and ideas here. Coming together nicely and extending existing linkages and rods is the right idea with this custom stuff. Lots of trial and error but using the KISS method seems to always keep the error part in check. Glad to see the Alvy crank made its way into this one. I chuckled the other day reading your install of the rear axles and the carpenter in you came out with your terminology in post #22. :biggrin2: Keep up the great work, love it!

Coming along, dual brake set maybe? looks like it will pop some wheelies for sure.

Yes, both sets of brakes are intended to work. TBD.

It's a cool build for sure, and I can't wait to see some video of it running. Hmmm - I got a couple 149's and a spare K341, maybe ---