Differential steering

[VroomVroom]

I was wondering if three differential could be attached together and used to drive tracks. The reason for three would be to prevent power loss while steering and anti slip on the " no traction side". My theory is that I'd use the middle differential (spider gears welded) to drive differentials on both sides. I then would mount a brake disk on the driveshaft yoke on each side differential. While the middle differential is turning, and the brakes are on, the side axles would have to turn. If the brake is released on either side, the yoke would spin and the side axle would either slow or stop depending on brake slippage. I thought in this fashion that the spiders are driving both sides and so both sides are geared the same and not speeding up to the opposite side that's stopped like a regular differential rear end would. The speeding up on a normal differential must rob power while turning and turn awful fast I'm thinking. Someone destroyed most of my equipment and need some type of tracked machine with a flat deck. I can't be picky and I have to try and make due with something. I haven't much time myself do do any of this. Anyone with knowledge of this could help me it would be much appreciated.

 

[buickanddeere]

You did not spec the size of the project. Low speed high torque hydraulic motors connected through a reduction drive . Forward reverse and variable speed for proper turning will be possible.
Differential brake steering is a power waster that stresses equipment .

 

[Renze]

I dont see the point. you are still slipping brakes, which is turning mechanical energy into waste heat.

Better would be a plain differential with a variable displacement hydraulic motor on one of the output shafts, and one on the diff cage itself, connected in series. Then you can steer by changeing the displacement of one motor, giving a speed difference between diff cage and output shaft with no slip losses, only a hydraulic efficiency of two times 0.8 is 0.64, for only the power difference between the two tracks.

A more advanced solution would be to add a planetary gear set so that the hydraulic motor becomes a sun gear, and will only rotate to generate a speed difference between both shafts, and not rotate when driving straight. This would further decrease friction losses, as high speed driving with the first mentioned solution will still mean that youre pumping around a lot of oil, with no pressure other than that to overcome flow resistance.

 

[bigdeano]

Military tanks use differential steering. Lots of info if you google differential steering. It acts like a variable ratio between the tracks.

 

[VroomVroom]

Yes. I realize I'm still losing some by slipping the brakes. But the yoke would normally be able to spin freely as it would not be connected to anything , whereas to get the sprockets to turn the yokes would be clamped to prevent moment, sending all the torque through to the side axle. It also wouldn't (gear up) the gearing to the side axles from the pinion to the spider gears. As both driven axles will only move using the spiders only. The pin ions would only spin when the brakes are released, causing the side axle to lose its power through the spinning yoke. If you fully released the brakes, the yoke would just spin, least resistant then driving the side axle(track).
I figured with just an open rear end you have to force a brake onto a side that's being powered. Then when it stops the other side has to speed up faster(gearing up) and cause more power loss. The way I figured you'd be just slipping the yokes which are not torquing anything but the mass of a brake disk. It is a loss, but no gearing changes from one side to the other. Hydraulics are great but the whining in my case is not desired. Argos will not stand up to the abuse the j5s did. Also, because whatever I had would be used by many people, I'd prefer it didn't skid steer. Even stopping one Sid altogether is not desired as over the rough terrain they'll tear the tracks off and bogie wheels etc. the j5s just slowed one side down. I have no idea. I need something that can take some punishment in the brush /woods. It does have to go fast, few mph at most. Many ten at tops, even slower. We'd only use the j5 in second and third and they can go 20mph in fourth on a dirt road if you pushed them.

 

[VroomVroom]

Probably an easier way to think of it would be to have one piece solid shaft inserted on one side of each differential, with a chain sprocket on it. The inner side of both differentials would always be turning while the chain is turning. What dictates if the side axles turn is whether the universal yokes of each pumpkin is braked or free to spin, thus sending the power that would have driven the side axle into a free spinning brake disk mounted on the yoke. The track would just roll at most or not at all.

 

[Mace Canute]

I was wondering if three differential could be attached together and used to drive tracks. The reason for three would be to prevent power loss while steering and anti slip on the " no traction side". My theory is that I'd use the middle differential (spider gears welded) to drive differentials on both sides. I then would mount a brake disk on the driveshaft yoke on each side differential. While the middle differential is turning, and the brakes are on, the side axles would have to turn. If the brake is released on either side, the yoke would spin and the side axle would either slow or stop depending on brake slippage. I thought in this fashion that the spiders are driving both sides and so both sides are geared the same and not speeding up to the opposite side that's stopped like a regular differential rear end would. The speeding up on a normal differential must rob power while turning and turn awful fast I'm thinking. Someone destroyed most of my equipment and need some type of tracked machine with a flat deck. I can't be picky and I have to try and make due with something. I haven't much time myself do do any of this. Anyone with knowledge of this could help me it would be much appreciated.

In a standard differential when one axle is not rotating, the other one does (at twice the speed) and the spiders are spinning on a pin. Those spiders are designed to rotate slowly for the most part just to allow for difference in rpm of the axles. Running them like you suggest will of necessity force them to spin as fast as possible when you are driving straight ahead and when one track is stopped the other track will double in speed and so will the spiders on that side differential and it is highly likely they will destroy themselves and the pin from inadequate lubrication in very short order, especially in a high load situation like your tracked vehicle would have.

You would be far better off to use a standard differential to direct drive your tracks and use individual brakes on each axle to effect a turn.

 

[VroomVroom]

Thanks. The way I figured, it wouldn't double when one side is allowed to freewheel. However, your right, the spiders would be spinning whatever speed I intended for the side axles/sprocket to turn. Thinking of how they work, in most cases while only going around turns they don't turn much. Thanks, that takes care of that idea.

Any suggestion on the open differential. I'd have to have the the sprocket so far from the vehicles side to mount 18 inch tracks. So I'd prefer having the brake disks inside the vehicle. I did see one video somewhere where they had the side axles just long enough to hold mounted brake disks, and some sort of coupling. They had the driven axles made in a square tube if I remember right, and extending long enough to mount the sprocket. Any ideas on this? I had over ten j5s. We need them. Now I'm trying to make anything which can be used for short hauls over rough swamping ground. I can make tracks, just need to drive them. We made them for the bombardiers.

 

[buickanddeere]

Military tanks use differential steering. Lots of info if you google differential steering. It acts like a variable ratio between the tracks.

Old WWII military equipment with an expected lifetime of hours ? Modern Military equipment?
Even bulldozers steer by disengaging the desired track's clutch pack for a majority of turns without getting into brake activation.. Self Propelled swathers are usually considered the best turning machine around and usually with the capability of full power to both drive wheels.
The Argo's of recent years from Ontario Drive and Gear use variable speed drive for most turns. Differential braking is for only the sharpest of turns.
Keep checking the classified ads. Sooner or later you can purchase a running 8WD Argo for less than the cost of a home built contraption,
ARGO 8-wheeled Amphibious All Terrain Vehicle | 700 HD UTV

 

[VroomVroom]

I have a 2013 hdi Argo. Great for getting the men around. Tougher then most would need or expect. The new steering is really good in them and a world away from the old types. But, we were use to driving into a location, trees, blow downs, mud etc without cutting a trail. And then putting two moose on and driving back out. I was looking for something built a little heavier. And thought an old pickup drivetrain for $500 and make up some tracks from conveyor belts I have for making the j5 tracks might have taken more abuse. Just don't know what to do

 

[bigdeano]

Old WWII military equipment with an expected lifetime of hours ? Modern Military equipment?
Even bulldozers steer by disengaging the desired track's clutch pack for a majority of turns without getting into brake activation.. Self Propelled swathers are usually considered the best turning machine around and usually with the capability of full power to both drive wheels.
The Argo's of recent years from Ontario Drive and Gear use variable speed drive for most turns. Differential braking is for only the sharpest of turns.
Keep checking the classified ads. Sooner or later you can purchase a running 8WD Argo for less than the cost of a home built contraption,
ARGO 8-wheeled Amphibious All Terrain Vehicle | 700 HD UTV

The M1 tank uses differential steering. The M60 tank used it 45 years ago. Caterpillar is using differential steering on a lot of their crawlers. I'm not talking about differential braking. Steering clutches are obsolete . I think the Argo uses variable ratio pulleys. That's not suitable for heavy equipment.

 

[buickanddeere]

The M1 tank uses differential steering. The M60 tank used it 45 years ago. Caterpillar is using differential steering on a lot of their crawlers. I'm not talking about differential braking. Steering clutches are obsolete . I think the Argo uses variable ratio pulleys. That's not suitable for heavy equipment.

The M1 series was supposed to get an update on the transmission and the fuel hog gas turbine. Same budget cuts that prevented the B52 being re-fitted with more efficient high bypass turbines . The money wasted on the F35 should have went to those projects. I was under the impression that most modern tracked vehicles first disconnected a drive clutch to the desired track. If a tighter was desired then that track's brake was applied.
If all electric drives are implemented . Clutches and brakes will be a mute point.

 

[bcp]

Free ideas here:

Notes on Tracked Vehilcle Steering

Buy an idea here:

A Low Cost Tracked Vehicle Steering System Design Providing Pivot Turning and Infinitely Variable Turning Radius

Bruce

 

[bigdeano]

You just need two differentials with the wheel flanges hooked together with a chain drive on one side and a gear drive on the other side. The wheel flanges on the second differential turn in opposite directions while the ones on the first turn in the same direction. If the pinion on the second differential is held stationary, the wheel flanges on the first differential are forced to turn the same speed in the same direction. If you have tracks driven by the first differential you will go straight.

If you turn the pinion of the second differential, say with a hydraulic motor, the tracks will turn at different speeds while still both receiving power. It's infinitely variable steering with small losses. The steering motor only handles a fraction of the power of the main drive.

 

[CNC Dan]

bigdeano has it right. I saw this setup in a Popular Mechanics magazine a long time ago.

The spider gears will be turning a lot in the stering axle, but for tracked vehicles the speed wouldn't be that high. Chose an axle with an easily replaceable third member and switch to full synthetic gear oil and you should be ok.

 

[FarmWrench]

Oliver OC-3 was true differential steering. One diff with breaks to turn. Very smooth for cultivating.

I didn't read the other replies but I wouldn't doubt someone has mentioned that if you replace the breaks on your "outside differentials" and connect them with roller chain and a hydraulic motor, you could achieve counter rotation. Cat D6 style.

 

[Fallon]

Free ideas here:

Notes on Tracked Vehilcle Steering

Buy an idea here:

A Low Cost Tracked Vehicle Steering System Design Providing Pivot Turning and Infinitely Variable Turning Radius

Bruce

Cool links. Never thought about track steering theory. One if these days I will get or make a crawler of some sort just because they are cool.

 

[VroomVroom]

If I was to slap a drive train and regular truck rear end with brake steering, my only problem now would be methods to have the brake drum or disks mounted so that a sprocket can be mounted and tire guides won't hook thr drum. Any methods or ideas ? I can't contact many who've built something on YouTube. I was thinking a c channel frame with two sprockets driving the tracks. And simple bogie system Flat deck to carry a little. Used just to retrieve moose off trail. Until I can replace a j5 or two. I can't open the above link or it seems you have to pay

 

[bcp]

This appears to be a source. Maybe they will do an interlibrary loan.

A low cost tracked vehicle steering system design providing pivot turning and infinitely variable turning radius (Book, 1992) [WorldCat.org]

Bruce

 

[Renze]

The M1 series was supposed to get an update on the transmission and the fuel hog gas turbine. Same budget cuts that prevented the B52 being re-fitted with more efficient high bypass turbines . The money wasted on the F35 should have went to those projects.

Here in Holland the same thing. The government kisses Lockheed Martins asses hoping to get a slice of the pie for our aviation components industry, but we're all being screwed by the consortium that builds the F35. Its development is funded by the US government and therefor there is no desire to get the thing actually operational, because revenue comes in whether its operational or not. Meanwhile the price tag for a single unit is exceeded more than double than when the contracts were signed with individual counties that wanted these.

Europe has some great fighter jets, the Swedish Saab Gripen and the French Dassault Rafale (Dassault is also the company behind SolidWorks by the way) but somehow the policy makers want to ride with the US because it would be easier to work in NATO joint missions... Well the way the US is ran economically these days, and how Putin rolls in the Crimea and Syria, soon we better buy a Russian MiG if we'd want to have the same thing as the worlds superpower....

America?s new trillion-dollar fighter jet under fire again - Fortune
COOLER M1 ABRAMS TANK ENGINES