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Ripsaw driveline

WaterH

WaterH

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So I’ve been watching a lot of videos on the ripsaw. I’m interested in the driveline as I have a similar project I maybe working on. In the videos I’ve seen they have a 9” diff in the center. Then they have two parallel disc rotors on each side with multiple calipers on each rotor. When I saw that, I figured there was an open diff in the center and the inner two rotors controlled steering like left and right tractor brakes. I figured the outer two rotors were the actual brakes.

In the last video I watched they gave a detailed explanation and I was wrong. First, inside the diff was a spool and it only powered the two inner rotors. If the calipers are actuated, they spin the second set of rotors which are connected to the tracks.

Now if you think about this, to turn right you must put some drag on the right side. That makes sense, but because of the spool, you must disconnect the inner and outer rotors. This seems odd to me. In addition, the inner two calipers rotate around the rotors. I didn’t really believe that at first, but I saw them in the video. Interesting to know how the brake lines are hooked up to those calipers.

So, I understand how it works, but I don’t understand why it was done this way. The way I explained it in the first paragraph seems like a better and simpler plan. Could someone on here she’d some light on this?

Edit for pic

B2782C92-8264-4606-BDA7-781CFAABA503.png
 
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basically it is ripsaw version of a dozer drive system

instead of a clutch on each side, they are using that wonky brake system to couple it
 
from what I have seen
they spend more time working on the Rip Saw thing than actually using it
 
They use brakes to differentiate the speed to steer. Why the use the brakes and calipers because they can take tons of abuse slipping. In reality all brakes do is slip.

A clutch setup doesn’t like to slip and to make one last at the speeds and power they are running would be really tough. They would have to spend xx,xxx on each ripsaw vs x,xxx dollars using off the self brakes.
 
WaterH said:
So I’ve been watching a lot of videos on the ripsaw. I’m interested in the driveline as I have a similar project I maybe working on. In the videos I’ve seen they have a 9” diff in the center. Then they have two parallel disc rotors on each side with multiple calipers on each rotor. When I saw that, I figured there was an open diff in the center and the inner two rotors controlled steering like left and right tractor brakes. I figured the outer two rotors were the actual brakes.

In the last video I watched they gave a detailed explanation and I was wrong. First, inside the diff was a spool and it only powered the two inner rotors. If the calipers are actuated, they spin the second set of rotors which are connected to the tracks.

Now if you think about this, to turn right you must put some drag on the left side. That makes sense, but because of the spool, you must disconnect the inner and outer rotors. This seems odd to me. In addition, the inner two calipers rotate around the rotors. I didn’t really believe that at first, but I saw them in the video. Interesting to know how the brake lines are hooked up to those calipers.

So, I understand how it works, but I don’t understand why it was done this way. The way I explained it in the first paragraph seems like a better and simpler plan. Could someone on here she’d some light on this?
Click to expand...

If you look closely the inner rotors are actuated by a rotating collar that carries the pressure to calipers. Those are essentially a clutch and the outer rotors are a brake. I’m guessing that speed, brakes probably aren’t required to initiate a turn.

The ripsaw has always appeared to me pretty low quality. I have that same thought again now that they are appearing on YouTube.
 
The problem with using a differential is that when you brake one side, the gearing of the other side is cut by half. And steering is when you need a lot more torque. Maybe not a problem in a high HP vehicle.

The Cletrac steering system was a simple way of addressing this, but had its limitations.
 
Only thing I think after watching the videos youdid is what a pieceof junk they are. Maybe his is just roched out but doesn't seem like great quality stuff there
 
Pukemaggots said:
The inner calipers act as a locker when going straight, when you turn and the outer calipers engage and the inners disengage.
Click to expand...

It has a spool. Doesn’t need a locker. The inner calipers act as a unlimited slip. If the inners disengage, the thing stops.
 
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Mikel said:
The problem with using a differential is that when you brake one side, the gearing of the other side is cut by half. And steering is when you need a lot more torque. Maybe not a problem in a high HP vehicle.

The Cletrac steering system was a simple way of addressing this, but had its limitations.
Click to expand...
Actually, the speed would double on the non brake side. Of course, you probably wouldn’t completely stop the one side for most steering.
 
WaterH said:
It has a spool. Doesn’t need a locker. The inner calipers act as a limited slip. If the inners disengage, the thing stops.
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You really have no concept of how it functions, yes is has a spool but a spool does not allow a tracked vehicle to turn. So when traveling in a straight line the inner calipers always have hydraulic pressure applied effectively locking the rear end. When you turn to the right the hydraulic pressure is removed from the inner right calipers and applied to the outer right calipers slowing/stopping the right side track causing the vehicle to turn. The same thing happens to the left side when turning to the left.
 
If it was just an open diff, there's a possibility it would just spin one track in low traction situations... that's no bueno when you are trying to steer using the tracks. Garage 54 just made a Lada screw drive vehicle that illustrates why an open diff doesn't work well in skid steer applications.
 
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I watched A documentary on the vehicles used in the mad max movie, ( Maybe it was here or the other place) but they were not impressed with the Ripsaws, I guess they had high hopes, but they were broke down most of the time, and couldn't hold up to the rigors of filming and the extreme conditions of the desert.

They always seemed like a rich guy novelty toy
 
This is described as steering clutches, and brakes in the dozer world.

First the spring applied/pressure released clutch disengages based on steering lever position (maybe 5%-25), further force on the steering lever (25%-100%) starts applying the brake keeping the clutch disengaged.

There is no power transmitted to the stopped track this the reason this system was abandoned for differential steering and hydrostatic drives.

"Diff" steering is 100% mechanical and provides full power to each track at different speeds.

This is a video of how the more complicated diff steer works.
 
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Pukemaggots said:
You really have no concept of how it functions, …..
Click to expand...

As I said “I understand how it works” . I’m asking why they did it this way. Your post just goes on to explain what I already know.

Juztyn00 said:
If it was just an open diff, there's a possibility it would just spin one track in low traction situations... that's no bueno when you are trying to steer using the tracks. Area 54 just made a Lada screw drive vehicle that illustrates why an open diff doesn't work well in skid steer applications.
Click to expand...

If you have left and right brakes, there’s no possibility to spin in a “low traction” unless you want it to.
 
Juztyn00 said:
If it was just an open diff, there's a possibility it would just spin one track in low traction situations... that's no bueno when you are trying to steer using the tracks. Area 54 just made a Lada screw drive vehicle that illustrates why an open diff doesn't work well in skid steer applications.
Click to expand...
*Garage 54
 
WaterH said:
As I said “I understand how it works” . I’m asking why they did it this way. Your post just goes on to explain what I already know.



If you have left and right brakes, there’s no possibility to spin in a “low traction” unless you want it to.
Click to expand...

Take an open diff and put cutting brakes on it, then go rock crawling. Sure you can brake the low traction wheel but if you've ever tried it it's a pain in the ass and it takes twice as much power as just having a locker

But there's a bigger problem I see in a tank application. With an open diff to go straight you have both brakes released. Now put some resistance on one track, head up a side hill or hit a good sized ledge with one track. With both brakes released it'd start turning on it's own. Sure you can correct for it but I'd imagine it makes for some unpredictable handling at speed. With this set up it goes dead straight until it's commanded not to.
 
Rugby said:
Only thing I think after watching the videos youdid is what a pieceof junk they are. Maybe his is just roched out but doesn't seem like great quality stuff there
Click to expand...

Exactly what I was thinking as soon as the popped the engine cover. Them showing how all of it was bent, broken and loose enforced it. It amazes me how people can build trash and get someone else to pay 100s of 1000s of dollars for it.

Also, hot rod duramax powering giant tracks through 1 9" diff? No thanks.

If they were smart, they'd just use 2 engines and cutting brakes. Probably be way more reliable and then the idiots with the giant checkbook can say they have TWO DURAMAX ENGINES! :homer:
 
rockyota83 said:
would wet brakes be better for this?
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Better yes, but significantly more expensive and complicated to set up I suspect.
Additionally when you fried them parts would be far more expensive and you would have to do something to cool the fluid.
Something like a torque converter on each side might be better? But also significantly more expensive.

Aaron Z
 
I've been watching these vids too, interesting setup all around. As these guys have noted, I see two reasons for it to be configured the way it is. Also noteworthy is I have zero experience with tracked tractors to see what the "norm" is.. First, is it genuinely acts as a spool when driving in a straight line versus having to actuate cutting brakes to keep optimal traction which decreases the knowledge necessary to operate it effectively. And second, if it were an open diff and you yank the cutting brake on one side, the gear ratio for the free spinning side cuts in half which means track speed doubles and you need twice the HP to keep it spinning

As far as being surprised that it only needs a 9" diff, the effective "tire size" it sees is the diameter of the cogged wheel at the rear that drive the whole system so it may only be in the 17-20" range from what we've seen so it's got quite a bit of gear reduction to its advantage. Though it has enough traction that even those smaller diameter cogs can see some pretty extreme torque, so interesting either way.
 
Effective tire size is small, but they're still huge heavy tracks in a large machine. Also it's all through 1 diff, not 2 like a 4wd.

I mean, I guess it works, I was just watching the latest video and it looked fun. The amount of suspension in the tracks is impressive. Using disc brakes in place of wet clutches is just dumb and is obviously problematic in those.
 
I know several have stated that it's spooled, but if you used, for instance, a TORSEN "T-x" diff, you could (theoretically) use it as a steering device...but your required electronic braking or potential slip force would be a total wild card, and (IMO) your maintenance would be off the charts. The mechanical wear of using the diff as a steering component would render this design moot after 3-5mos. Can't see another way to use braking to help steering.
 
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YotaAtieToo said:
Effective tire size is small, but they're still huge heavy tracks in a large machine. Also it's all through 1 diff, not 2 like a 4wd.

I mean, I guess it works, I was just watching the latest video and it looked fun. The amount of suspension in the tracks is impressive. Using disc brakes in place of wet clutches is just dumb and is obviously problematic in those.
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Oh yeah not saying it’s the perfect solution, and it sounds like this one being 15ish years old is one of the earliest ones they made. I have no clue, but I would assume they learned a bit from these early versions and made improvements as they stepped into gov models. In one of the earlier videos they tested the top speed and ran out of gear around 60mph with the stock diesel trans. So while they’re asking a lot out of a single diff, the sheer amount of reduction in the system also relieves a lot of the usual stress differentials see
 
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