B7100D HST transmission power transfer

[KuBoata]

Hi all,

I am working on a project paddlewheeler boat that is using a salvaged B7100 for power. Right now I am confused as to the reverse functionality of the hst. I would LIKE to utilise the motor and HST to power the paddlewheeler. I don't want the heavy gearbox or axle. I assume that this is possible because the reverse pedal simply reverses the flow of the fluid. The gearbox doesn't affect this, it only controls speed and pto/4WD. Is this assumption correct?

I'm sure I will have more questions as I go on, and I will post photos as I progress. Thank you!

 

[Lencho]

Get the WSM to see how it all fits together.
http://kubotabooks.com/AutoIndex/in...wners Manuals/&file=B7100HST_WSM_complete.pdf
I would think you need to gear it down to turn a paddle wheel?
Plus we need Photos!!!

 

[North Idaho Wolfman]

Yes an HST does not need a gearbox to reverse.
You'll need a gearbox to do a gear reduction otherwise you will not have any torque and way too much speed.

The HST will need a large sump with some sort of cooling ability (cooler with an electric fan or engine fan) or you will burn up the HST.

I would not recommend running this like a traditional boat, I would suggest a radiator with a closed loop cooling system because I'll bet (like 100%) on that model D750 you have, that it does not water pump or thermostat.

 

[KuBoata]

Thanks for the info gents. The paddlewheeler is actually an 18 ft pontoon with a paddlewheel that was set up with an electric motor that I picked up at an estate sale. The paddle itself is chain drive so I am planning on using a 90* gearbox (or worm drive) off of the hst with a proper reduction and a sprocket of appropriate size tacked to it. This is going to be a shallow water work platform primarily so doesn't need to be pretty. I plan on using the gear output of the hst for the wheel and maybe running an alternator off the PTO output. Plan on lots of lights and a winch in case I get stuck in the swamp.

I know I'm also going to need to fabricate a tank for the hydraulic fluid pickup,etc if I lose the gearboxes. Also, I plan on using closed loop cooling as suggested. Will most likely use the radiator that is on the tractor basically just mount the front half of the tractor without front axle or steering...
Enclosed pic of the pontoon so far...

Anyway,. Is the hst output 1:1 to engine rpm on both shafts? Thanks!

 

[100 td]

No more answers until the pics are posted, or else! (You just posted before me)
Edited rough calcs, (may have used metric speed)if they are correct, 102 rpm axle speed in high range, 40 rpm in low range, at 2800 rpm in high gear.
Diff pinion shaft speed, = rpm / differential reduction - .162, = 629 for high range.
Guessing that high gear is 1:1, could be very wrong. So guessing that the HST runs at 629 rpm.
You would have to check the gearbox ratio, as may not be 1:1, could be something totally different. NIW, whitetiger or others may know or they may know what speed the HST motor runs at. Info may be available in manuals or documentation, I just grabbed the diff ratio from the parts book. You may be able to find gear ratios from the parts book or service manuals, not sure if they are listed, I only looked at the diff.
What maximum output shaft drive speed are you looking for to mate up with what you have?

 

[100 td]

So it wouldn't have been easier to have a generator to drive the existing electric motor and supply power for lighting? What size is the electric motor, how many rpm, and what is the current reduction box it's driving?

 

[KuBoata]

So it wouldn't have been easier to have a generator to drive the existing electric motor and supply power for lighting? What size is the electric motor, how many rpm, and what is the current reduction box it's driving?

Yes! Except this project sat for who knows how long, so the electric motor was shot (magnets were literally flaking away). Plus, the gearbox on the boat was only rated for .7hp and a 1:1 ratio.

So plan b was... I had this old Rusty tractor sitting in the yard...

Plan c is a nice lawnmower / gas engine with a horizontal shaft. But I don't have one of those just laying around! Plus, I just have this genetic defect that requires me to do things the most difficult way possible!

 

[100 td]

YPlus, the gearbox on the boat was only rated for .7hp and a 1:1 ratio.

What rpm was the electric, and what rpm do you eventually want out of the kubota drive?

 

[100 td]

I guess with the kubota you'll want to get this up on the plane!

 

[100 td]

One thing you may wish to consider if you use the kubota, a slip clutch of some sort other wise you may do some damage, break chains or worse if the paddle catches on anything or you accelerate too fast.

 

[KuBoata]

So, the motor was .5hp @ 1750 rpm. The existing 90* gearbox is 10:1 and the chain sprockets are 15t to 70t which gives us 4.6:1 which results in a 1750/46.6 = 37.5 rpm on the paddlewheeler. (Feel free to correct if math is wrong).

I'm not sure what's optimal... Need to to research. Been spending my time getting a 40 year old rustbucket running and disassembled.

slipper clutch might be a good idea, but the wheel is made out of Trex and angle aluminum so not sure if the paddles won't break before the slipper kicks in... ? Besides we are mostly swamp/ mud around here. Not allot of rocks, just the occasional fallen tree branch

 

[KuBoata]

The graveyard and my current runner. I got the two 7100s and 7200 along with a pile of implements from an old guy who was moving to the city. 7300 is my current runner.

 

[100 td]

slipper clutch might be a good idea, but the wheel is made out of Trex and angle aluminum so not sure if the paddles won't break before the slipper kicks in... ? Besides we are mostly swamp/ mud around here. Not allot of rocks, just the occasional fallen tree branch

I think something like this in replacement for the electric motor would be better with a slight change in sprockets. One stick on the paddle with the Kubota and you destroy it.
https://www.ebay.com/itm/192524178041

 

[KuBoata]

Hah! A small gas engine may work fine... But I have the Kubota so I'm going to use it. I intend on using a trolling motor for emergencies. If I bust the wheel ... Well then I will have to build a stronger one

 

[100 td]

So, the motor was .5hp @ 1750 rpm. The existing 90* gearbox is 10:1 and the chain sprockets are 15t to 70t which gives us 4.6:1 which results in a 1750/46.6 = 37.5 rpm on the paddlewheeler. (Feel free to correct if math is wrong).

So if you run the engine at ~1400 you have 0~50 rpm available at the rear axle, 1:1 to the chain drive.
Or 1400 rpm ~315 at HST, 15/70= 0 to 67 rpm, put a stop on the skinny pedal.........

 

[KuBoata]

Thank you. I also wanted to point out that I would like to reuse the hst for the reverse capability. Something I won't have with a motor hooked up to a chain...

Also, I am not going to keep the 90* gearbox currently on the boat. Thanks for the insight!

 

[North Idaho Wolfman]

If you wanted to make it one super tough unit, change the paddle wheel arrangement slightly and run it off a small auto axle, that would give you the gear reduction needed and shaft drive, super dependable and super strong!

 

[100 td]

So if you run the engine at ~1400 you have 0~50 rpm available at the rear axle, 1:1 to the chain drive.
Or 1400 rpm ~315 at HST, 15/70= 0 to 67 rpm, put a stop on the skinny pedal.........

These figures are for direct drive, 10:1 gearbox omitted.

Using whole kubota box/axle, engine at ~1400 you have 0~50 rpm available, 1:1 to the chain drive.

Using just the HST with the 15 tooth sprocket on the output shaft engine at 1400 rpm ~315 at HST, 15/70= 0 to 67 rpm for the paddle