T-20 reduction ratio in forward/reverse

[BobW]

Hi.

I am working on my "tank" project and just received a DuroMax 16hp engine, so I'm getting ready to install a drivetrain. I noticed something interesting about the T-20. It's being installed way differently than in a MaxII, such that it will be running in "reverse" while running forward. That is, I am running the T-20 backwards. It seems like the T-20 normally has a 6.25:1 reduction when it reverse and a 5.25:1 while in forward. At least mine does. So, is there anything bad about running a T-20 backwards other than messing up its intended distinction of forward and reverse ratios? If there is another reason not to run it backwards, I'll change something for sure. Otherwise, I may use it this way.

Thanks.
Bob

[LarryW]

Im guessing you are making your own tank then? I would run it so the pulley is on the left side of the machine. Im not sure if it would hurt to run it the other way or not but better safe then sorry.

[thebuggyman1]

Hi Bob, Glad to see that you are going forward with the project this quickly.
Internally, the t-20 lubricates by "splashing" fluid with the drums. Either way the drums turn, it would still splash.
The problem I see, is if you planned on turning the input shaft in reverse.....I think you would need to flip the secondary clutch around so that the torque applied would still work with the ramp angle and shift up/down properly.

[LarryW]

The motor should spin the same way so I think he is talking about flipping it around so the motor pto is on the right side instead of the left. But then the controls would be on the wrong side unless its front mounted. In that case forward and reverse on the sticks would be backwards but if the t-20 is backwards then it would be right. Oh gezz, I think I hurt my head trying to figure that out. I may be wrong, lol. If its a custom job I would just do it the way Max did unless its to late in the fab process. In that case I would just turn the seat around and put the headlights on the back, lol.

Bob, could you fill us in more on what your doing? Or a picture maybe?

[thebuggyman1]

I would just turn the seat around and put the headlights on the back, lol.

This is why Recreatives and ODG will never have to worry about "Larry's Amphibious Machines & Engineering".....L.A.M.E.

[Mike]

This is why Recreatives and ODG will never have to worry about "Larry's Amphibious Machines & Engineering".....L.A.M.E.

[coosaridgerider]

If you are running the duramax motor in a confined area you might want to relocate the gas tank from the motor.I put this motor in my stepsons argo and run it about 30 minutes when i noticed gas running out of the breather.This was caused by the tank getting hot and pushing the gas out the breather tube ,When i opened the gas tank cap the gas was boiling in the tank.After relocating the tank the motor ran alot better.

[BobW]

Hi, Jim, All.

Here is something that is different than the standard layout, given that this vehicle is not the usual AATV. The engine is in the rear with a primary clutch (to be purchased soon, maybe eBay item 140865404526) on it like normal. Then, that goes to the secondary in a standard fashion, except the secondary is on a jackshaft. Also on this jackshaft is a chain sprocket with a chain that goes to the front of the vehicle to meet a sprocket on the input of the T-20.
tks_oct15b.jpg

The piston leaning to the one side is making me want to mount it the way you see. If I turn the engine around, I lose about 5-6" of seatback room, which would be sad. I also liked the way my T-20 control stick would work before noticed this strange gearing difference based on relative direction of rotation.

My build thread is here:
http://www.scaledtanks.com/e107_plug...ic.php?47541.0 In this picture near the bottom of the thread I show the DuroMax in place and the secondary clutch more to the vehicle rear. The engine is behind the passenger, and the T-20 will be at the feet of the driver.

The gas tank will be a 4.5 gallon flat tank mounted at a level of the old tank, but not over it. The is some confinement, but also some ventilation, and there will be active fan power.

I wasn't sure if there was a factor were the band brake is happier always gripping or always lose on the drum, thus it was better to run counter-rotating or same-rotating for most of the time.

[Mike]

Which side of the vehicle is the input sprocket on the T20 located? I would assume the jackshaft has its sprocket that is feeding the chain up to the T20 on the opposite side of the clutch. If so, that would put the input sprocket of the T20 on the right side of the vehicle. I guess a better way of saying that is that the input sprocket on the T20 would be located on the opposite side of the vehicle as the clutches on the motor and jackshaft?

If so, can you just switch the the sprocket on the jackshaft to the same side as the clutch?

[LarryW]

Ok I see what your doing know. I had to join scaledtanks to see your thread though. Looks like a cool project.

I think I would still run it the way it is suppose to be. Then with linkages you can figure out a way to work the controls over or under the t-20. I haven't had to tear into a t-20 yet but typically reverse works by running through another set of gears. Thats just more moving parts to wear. But I dont think you drive those tanks for miles and miles every weekend. (Or do you?) It will probably be fine for what your doing.

I bet you could build it to float! A floating tank would be cool!

Mike,
His t-20 input is on the right side. What your saying would work, with the sprocket on the same side as the driven clutch. And spin the t-20 around so input is on the left. Also its pretty wide you could probably just move the whole engine/jackshaft over.

[BobW]

Mike got the layout correct. See, the engine, being CCW output shaft is going to pull the drive chain along the chain bottom. Say this chain was directly attacked to the outside sprocket driving the track (or wheel), it would already be rotating in the correct direction. That is why the T-20, no matter how it is positioned will be same-rotating to drive forward, and counter-rotating to go in reverse. The only solutions would be to reverse the engine direction, flip the engine, add a rotation reverser in the chain. That's all I could think of.

The tankers don't seem to run as hard/long as the AATVers. Floating is probably not in the cards. I'll be happy if it just drives. Not even caring to use the zero-turn feature.

[LarryW]

I give up, lol.

[BobW]

You know what's funny is I am not even used to seeing the normal mounting of the T-20. I've only known it as a brick of steel in my shop.

Sorry, Larry.

[LarryW]

You know what's funny is I am not even used to seeing the normal mounting of the T-20. I've only known it as a brick of steel in my shop.

Sorry, Larry.

I tried to give up but couldnt. I also figured I better think before I type so I dont have to edit my post a be jillion times. But my current thinking is....

You need the t-20 output and input to spin the same direction in forward motion so the reverse gears wouldnt be spinning all the time. Anybody feel free to correct me if I am wrong. So if your motor pto is on the left you should be fine with the t-20 input on the right.

[msafi65]

I think the t20 is stronger in forward with the shift collars locked into the hardened drive plates. In reverse the collars are locked into the hardened cast teeth of the ring gear drum. I've seen numerous failures of the reverse teeth. Mostly from misuse but I've not seen a drive plate tooth failure. The input shaft can be installed on either side of a t20. I would set it up to travel forward with the shift collars to the inside position locked into the drive plates. Just my opinion.