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PRINCETON_JAKE

True Bogger
Registered: 04/05/11
Posts: 130
Reply with quote  #1 

ive read that some guys are going to run, or try to run 5 ton rockwells since planetaries are so heavy and expensive, and there are people like gearhart building upgrded parts for them. So has anyone been/started using 5 tons? how are they holding up compared to custom built planets

tntmonstertrucks

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Registered: 04/11/11
Posts: 67
Reply with quote  #2 

we built a turn ket race truck with 5tons  months ago   but we made up king pin braces for the upper and lower pins  and had to wrap the knuckles.  it hold up  but i wouldent be doin monster jam free style  with 5tons. and when your done its not a whole lot of weight difference  than 106s with clarks

gearharteng

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Registered: 11/08/11
Posts: 58
Reply with quote  #3 
5 tons in freestyle monster jam would work just as well as clarks with 106 combo, a lot cheaper. To get the planetarys to hold up it requires custom axle shafts, kingpin girdles,
billet spindles, and a lot are going to billet,or fabricated outer knuckle. I know because I am working some for a top team. And you still see wheels lock up, gears break,axles break.And price a set of 20 ton clarks if you can find them, would 5 ton axles work in stock form not even close but with the proper parts they would be just as durable with some performance advantages

PRINCETON_JAKE

True Bogger
Registered: 04/05/11
Posts: 130
Reply with quote  #4 
Quote:
Originally Posted by tntmonstertrucks

we built a turn ket race truck with 5tons  months ago   but we made up king pin braces for the upper and lower pins  and had to wrap the knuckles.  it hold up  but i wouldent be doin monster jam free style  with 5tons. and when your done its not a whole lot of weight difference  than 106s with clarks

 

I dont see why a custom axle like gearharts would be any less stronger then a planet axle, and in my eyes (and people i know) the problem with planets is they rob a TON of power, and in a mud truck getting enough wheelspeed can be a problem

Sofa King

JUSSA WANNABE BITCHES
Registered: 04/03/11
Posts: 968
Reply with quote  #5 
Quote:
Originally Posted by PRINCETON_JAKE
Quote:
Originally Posted by tntmonstertrucks

we built a turn ket race truck with 5tons  months ago   but we made up king pin braces for the upper and lower pins  and had to wrap the knuckles.  it hold up  but i wouldent be doin monster jam free style  with 5tons. and when your done its not a whole lot of weight difference  than 106s with clarks


I dont see why a custom axle like gearharts would be any less stronger then a planet axle, and in my eyes (and people i know) the problem with planets is they rob a TON of power, and in a mud truck getting enough wheelspeed can be a problem


gearharts doesnt make the knuckles do they?? that seems to be the weak spot.. and i have yet to see a monster truck that had a problem with wheel speed.. just sayin..

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iniviate

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Registered: 03/24/11
Posts: 8,618
Reply with quote  #6 
Quote:
Originally Posted by PRINCETON_JAKE
the problem with planets is they rob a TON of power



if the overall gearing is the same, what does it matter if the gear reduction is in the t-case or the hub?



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Quote:
Originally Posted by mcreynoldsair
if your going to change your screen name need to change how you wright

no punctuation and you spelled dozier wrong
collateral damage

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Registered: 04/03/11
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Reply with quote  #7 

Quote:
Originally Posted by iniviate
Quote:
Originally Posted by PRINCETON_JAKE
the problem with planets is they rob a TON of power



if the overall gearing is the same, what does it matter if the gear reduction is in the t-case or the hub?


i thought the same thing but i forgot who it was off chucks i was talking to but he said in planets you have drag in the t-case gears and center section of the axle gears and then the drag of the planet gears and with a 5 ton you just got the case and the center gears
it made sence but ..... 

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tonka tester

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Reply with quote  #8 
Quote:
Originally Posted by collateral damage

Quote:
Originally Posted by iniviate
Quote:
Originally Posted by PRINCETON_JAKE
the problem with planets is they rob a TON of power



if the overall gearing is the same, what does it matter if the gear reduction is in the t-case or the hub?


i thought the same thing but i forgot who it was off chucks i was talking to but he said in planets you have drag in the t-case gears and center section of the axle gears and then the drag of the planet gears and with a 5 ton you just got the case and the center gears
it made sence but ..... 
with planets, youd have a lot more gears spinning to make it go than with  a single case with a chosen gear ratio and 5 tons  
driveshaft speed would be different too

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http://i990.photobucket.com/albums/af30/tonkatester/Picture103.jpg looking for a tire like this (66x43x25)

THE MONSTER
http://www.tgwforums.com/post?id=5168515
the jeep
http://www.tgwforums.com/post/planetary-axled-flatfender-jeep-on-air-ride-with-a-turbo-new-pics-roller-now-6159179?pid=1276433439#post1276433439


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Sofa King

JUSSA WANNABE BITCHES
Registered: 04/03/11
Posts: 968
Reply with quote  #9 
So why did all the monster trucks switch to planets???
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tonka tester

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Reply with quote  #10 
Quote:
Originally Posted by Sofa King
So why did all the monster trucks switch to planets???
because they weighed 20,000 lbs back then... and they had 8" of suspension travel, and the 5 tons had no aftermarket support then.  

__________________
http://i990.photobucket.com/albums/af30/tonkatester/Picture103.jpg looking for a tire like this (66x43x25)

THE MONSTER
http://www.tgwforums.com/post?id=5168515
the jeep
http://www.tgwforums.com/post/planetary-axled-flatfender-jeep-on-air-ride-with-a-turbo-new-pics-roller-now-6159179?pid=1276433439#post1276433439


●█〓██████▄▄▄▄▄▄▄ ●
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██████USA████████
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PRINCETON_JAKE

True Bogger
Registered: 04/05/11
Posts: 130
Reply with quote  #11 
Quote:
Originally Posted by Sofa King
Quote:
Originally Posted by PRINCETON_JAKE
Quote:
Originally Posted by tntmonstertrucks

we built a turn ket race truck with 5tons  months ago   but we made up king pin braces for the upper and lower pins  and had to wrap the knuckles.  it hold up  but i wouldent be doin monster jam free style  with 5tons. and when your done its not a whole lot of weight difference  than 106s with clarks


I dont see why a custom axle like gearharts would be any less stronger then a planet axle, and in my eyes (and people i know) the problem with planets is they rob a TON of power, and in a mud truck getting enough wheelspeed can be a problem

 

 

http://www.tgwforums.com/post/some-more-5ton-beef-5175896?highlight=gearhart


gearharts doesnt make the knuckles do they?? that seems to be the weak spot.. and i have yet to see a monster truck that had a problem with wheel speed.. just sayin..
tntmonstertrucks

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Registered: 04/11/11
Posts: 67
Reply with quote  #12 

the thing is now  the parts are ready and avalible  for the clarks  and theres mostly  just talk about the aftermarket parts for the 5tons and no set pricing..   look at the stock size difference  of the king pins.plus the only way you can truly convince  90% of the mt guys to switch  is if  patrick   told guys they were the way to go lol 

mudevil

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Reply with quote  #13 

Are we talking about 5 ton top loaders or a SQHD? I can't see monster trucks switching back to top loaders.

PRINCETON_JAKE

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Registered: 04/05/11
Posts: 130
Reply with quote  #14 
Quote:
Originally Posted by mudevil

Are we talking about 5 ton top loaders or a SQHD? I can't see monster trucks switching back to top loaders.

 

I agree Loren, would a built hybrid f106 center section hold up if it had 5 ton outers and axle shafts?

MUD SLUT

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Posts: 1,310
Reply with quote  #15 
Quote:
Originally Posted by PRINCETON_JAKE
Quote:
Originally Posted by mudevil

Are we talking about 5 ton top loaders or a SQHD? I can't see monster trucks switching back to top loaders.

 

I agree Loren, would a built hybrid f106 center section hold up if it had 5 ton outers and axle shafts?



That doesn't really change anything. The weak points of the 5ton, in a monster jam setting, regardless of what's available in the aftermarket, lie in the shafts, knuckle, and spindle. In that setup, you still have all the 5 tons weak points....

After I go get some grub, I'll come back and take y'all to school on axles and answer why the monster trucks switched, including iniviate's question.

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Quote:
Originally Posted by iniviate
Who on 72"+ tires can do better than that?
Quote:
Originally Posted by z71on46s
I will monster truck your shit!
Quote:
Originally Posted by adamsnotsoperformance
oops read that backwards.
Quote:
Originally Posted by damnyankee
I've built everything on mine and you make me want to throw rocks at it.
Quote:
Originally Posted by ON TIME
SHUT THE F#CK UP CORKY!
mudevil

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Reply with quote  #16 
Quote:
Originally Posted by PRINCETON_JAKE
Quote:
Originally Posted by mudevil

Are we talking about 5 ton top loaders or a SQHD? I can't see monster trucks switching back to top loaders.

 

I agree Loren, would a built hybrid f106 center section hold up if it had 5 ton outers and axle shafts?

 

Nope. The planets are the only thing keeping them alive.

adamsoffroadperformance

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Posts: 612
Reply with quote  #17 

There is no stock axle of anykind that will hold up to MonsterJam freestyle in stock form. Look at any truck running today and they are all modifed pretty far from stock to take the abuse. The reason a planetary has more drag than say a tcase is because there is alot more surface area contact in a planetary than in a t case style setup. More surface area equals more friction and thats all there is to it. And the reason for most trucks switching to planets was as Tonka said. 30yrs ago a monster truck was 15k lbs or more had very little suspention travel which also was a stiff travel and had heavy wheels and heavy full cleat tires. Today's trucks can be built lighter and have 20+ inches of travel that is dampened by a hightech shock and the lightweight wheels and shaved tires of today also have relieved alot of the stress's that turned many guys away from 5tons. There are quite a few monstertruck guru's that are still running today that will tell ya that they got away from the 5ton before they should have. You all can speculate what would work what won't but when there are guys like Mike Vaters, John Seasock, Dave Rife, Everett Jasmer, Allen Pezo, Kid Rarig, Bob Shea, and many more I can keep naming, that all ran 5tons back in the day and are confident that a properly prepped 5ton will work and work very well at that gives a little more firm ground to stand on.


__________________
the planetary trucks break pinion shafts occasionally. the 5 ton trucks don't.

Quote:
Originally Posted by stevessuperduty
the true mud bogging in the good mud will always happen behind the scenes in the woods on private land.



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http://www.gearharteng.com
MUD SLUT

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Reply with quote  #18 

Quote:
Originally Posted by mudevil
Nope. The planets are the only thing keeping them alive.

Yes, I also forgot to mention you got rid of one of the 5ton's strong points, the chunk, and traded for a weaker one. And yes, f-106's have enough trouble staying together WITH the planets helping them out... Ring gear failures are quite common at events.

Quote:
Originally Posted by adamsoffroadperformance
The reason a planetary has more drag than say a tcase is because there is alot more surface area contact in a planetary than in a t case style setup. More surface area equals more friction and thats all there is to it.


Not quite and I'll put it to rest in a much longer, separate post here momentarily as I got too tied up last night.

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Quote:
Originally Posted by iniviate
Who on 72"+ tires can do better than that?
Quote:
Originally Posted by z71on46s
I will monster truck your shit!
Quote:
Originally Posted by adamsnotsoperformance
oops read that backwards.
Quote:
Originally Posted by damnyankee
I've built everything on mine and you make me want to throw rocks at it.
Quote:
Originally Posted by ON TIME
SHUT THE F#CK UP CORKY!
adamsoffroadperformance

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True Bogger
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Posts: 612
Reply with quote  #19 

Please teach us master


__________________
the planetary trucks break pinion shafts occasionally. the 5 ton trucks don't.

Quote:
Originally Posted by stevessuperduty
the true mud bogging in the good mud will always happen behind the scenes in the woods on private land.



http://www.adamsoffroadperformance.com

http://www.gearharteng.com
MUD SLUT

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Posts: 1,310
Reply with quote  #20 

Quote:
Originally Posted by iniviate
Quote:
Originally Posted by PRINCETON_JAKE
the problem with planets is they rob a TON of power

 

 

if the overall gearing is the same, what does it matter if the gear reduction is in the t-case or the hub?

 

 

 

Quote:
Originally Posted by Sofa King
So why did all the monster trucks switch to planets???

 

Quote:
Originally Posted by adamsoffroadperformance

Please teach us master

 

Gladly, Adam. Better getcha popcorn ready...

 

Let me explain those questions and set the TGW record for longest reply in one swift move. 

 

 

 

People say planets suck horsepower....well, that is an often misused term. Horsepower is nothing more than work over time or more relative, torque at a speed, where work and torque are synonymous as well as time and speed. High horsepower means high torque at high speed. If we lose speed and torque stays the same horsepower still goes down. That's why a highly efficient diesel engine's horsepower is usually about 1/2 the torque and a high performance gas engine's horsepower is very near the amount peak torque. ex hiperf diesel 700hp 1400ftlbs of torque or high perf gas 700hp 700tq The diesel clearly makes more real power ie torque, but the engine moves at half the speed(3000rpm vs 6000rpm) of the gas, so it makes half the horsepower with double the torque output. In reality, the diesel has more real power ie more torque and will win a race against that gasser time and time again with the same hp because it makes double the "real" power.

 

Here's another ex.

Horsepower= Torque X RPM   OR Torque= 5252 X HP

                       5252                                RPM

 

A motor for a garage door opener spins at 10 rpm and has a 1/3hp rating. What's the torque? A dremel tool spins at 30,000rpm and has 2ftlbs of torque. What's the horsepower? Which one has the greater potential to hurt you if you end up on the receiving end of one?

 

Let me show you.

For the garage door opener, the constant 5252 times .3hp divided by 10 rpm equals 157.56 ft-lbs of torque, as much or more than a 4-cyl honda. The dremel makes 2ft-lbs times 30,000rpm divided by the constant 5252 equals 11.42hp. The garage door opener clearly makes more torque and has more potential to hurt you, but the dremel still has 11.1 more horsepower...And, the dremel with more hp still could never open the door because it has no "real" power, torque. The garage door opener makes substantially more power, just at a lower speed. Speed/horsepower is not power....it's power over time. The dremel has more horsepower so it has the capability to do more work at its torque than the opener. If we were to use the opener motor for "dremel work" ie sanding/grinding it could do massive work with 157ft-lbs, but it can't do it fast with only 10rpm....that's why the dremel is built with high horsepower in mind. Once again, Speed/horsepower is not power....it's power over time.

 

So, if by horsepower, we mean speed, then yes, anything that reduces output speed of the motor(like a t-case, a 5ton, a planet) is reducing horsepower and at the same time generating torque which is what we all try and tune for. A planet, a 5ton and a low range t-case ALL are speed reducers, hence the term, "gear reduction"; but this will not change real power if we compensate for it. The changing of speed does change torque output, but......speed is easily "compensated" with more or less gearing and the torque can remain the same.(within the realm of the powerplant in question) If I put planets on my 5ton truck and change nothing else I will in essence "lose horsepower" by losing wheelspeed and at the same time I'll generate MORE in torque. How much? Exactly the inverse of the amount lost in speed, but my engine's torque and horsepower outputs are the SAME!!! So, if that is true, then I can regear and gain that lost speed, or "horsepower" if you will, right back... So essentially all that was lost from speed reduction was recovered through speed multiplication an no "real" power was lost, until we bring up the real power robber......efficiency.

 

ALL axles rob power. Nevertheless, you're comparing a planet to a 5ton rockwell; which isn't exactly the most efficient design, being a double reduction unit. The toploader unit is quite parasitic from a design-efficiency standpoint, maybe better than a typical planet, but the planet could still be better depending on how it's geared, the torque, and gear speed. First, consider this.....then I'll explain the axle differences/efficiencies.

 

In any gear system, output power equals the input power minus the power losses. Power losses in gear systems are usually associated with friction between teeth and lubrication churning losses. Churning losses are relatively independent of the nature of the gears (straight cut vs. hypoid cut) and the gear ratios themselves, which is directly related to the speed of the gears passing through the fluid. Churning losses are difficult to calculate so they either leave them out or use estimates based on experience in initial gear design. The important thing is the more torque or speed sent through, the less power is lost from churning. The frictional losses are related to the gear design, the reduction ratio, the pressure angle, actual gear size, and the coefficient of friction. The important thing here is the more torque or speed sent through, the less power is lost from friction.  This will come into play later...

 

Now, in addition to the losses mentioned above, every time you compound the system by adding more gears or systems of gears, additional losses must be factored in, but keep in mind that the more torque or speed sent through, the less power is lost. Let's take a look at a typical monster truck system. We have the output torque coming from the engine, geared through the transmission, then geared further through a transfer case or cases, then being transmitted through the drive shafts into the axles, and from there the power goes through another gearset (or gearsets in the case of a toploader or planetary axle) before finally reaching the last piece in the system, the tire and wheel, where all of the power output is directed. (tire=gear)

 

With that said, from the engine on downstream, every time input power is transmitted through a gear system, although some of the output power is generated into more or less additional torque and/or speed is increased or decreased, an amount of that output power is/was lost in the creation of motion. Some energy is lost through heat, sound, friction, fluid churning, rotational mass, etc, as it passes through each system; some in the transmission, some in the transfer cases, some in the axles, and so on until we reach the wheels. Okay.

 

Now I'll answer iniviate's question. Since we are interested in axles in this thread, we will ignore everything further upstream in the powertrain until later. For now, just think axles. How can the planetary axle, by itself not including ratio, gear speed, or torque, be only slightly less efficient than everyone's been telling me?

 

Here's how. First, I'd like to point that nearly ALL gear sets except a worm gear are 90% efficient or better(google it), so at worst, a 10% or less difference in efficiency is what we're seeing. Rough estimates ignoring gear ratios, gear speeds, and torque are telling me that a 5ton toploader is about 96% efficient, where a typical axle is 98-99%. Going through a set of spurs and a set of hypoids together nets you a 4% loss. That's 1% more efficient than a single stage planetary like I run, which was estimated at 95% after losing 5% through the hypoid gearset and the single stage planetary together. This ignores gear ratio, gear speeds, and torque; which can make the number go up or down a few points, but stands as a decent axle to axle comparison at this point. Remember, numerically higher gears or ones that give the most mechanical advantage, transmit the most torque, and as such, see the lowest losses, and as we speed any gearset up theses losses in efficiency matter less in a "controlled gearing system". Planets have numerically higher gears with more gears spinning faster. I'll make the "non-planetary fanatics" happy after I say this first.....

 

The planetary arrangement is an engineering design that offers a few pluses over a conventional gearbox arrangement, but they must fit the application. The major advantage being its unique combination of high power density(the real secret lol), low gearing (the other secret), compactness, and, yes, outstanding power transmission efficiencies due to spinning more gears faster. A typical efficiency loss in a planetary gearbox arrangement is only 3% per stage. (One stage includes the ring, planet, and sun.) A typical gearset would be double at around 6% to do the same reactions and achieve the same results, at the same sizes. This type of efficiency, through pure torsional reactions, ensures that a high proportion of the energy being input is transmitted through the gearbox, rather than being wasted on mechanical losses inside the gearbox. Please note, that 3% loss is only regarding the planet gear system, per stage; yet in any planetary axle, we have another set of gears (usually hypoids) to run through yet, netting additional loss, typically 1-2%. Even still, planetary gear design is highly efficient at giving large gearing in a small package when compared to a similar sized set or sets of conventional gears and these things increase efficiency. Due to dimensional constraints and practicality, you typically won't see spur gears over 6:1 ratio or hypoids at more than 10:1 in a single stage. Similar to the fact that a 2:1 planet cannot exist, a 10:1 shouldn't, and 5:1 is the best. (WTF?--ask and I'll elaborate) At those higher ratios, the traditional systems either have low power density, become inefficient, unpractical, or geometrically impossible. We can compound smaller ratios with spur or hypoid gears to achieve the larger gearing the design calls for, but at the expense of additional losses through more gears, seeing more torque throughout each stage in the overall system, combined with lower power density and more size to the overall system and less efficiency. Ever take apart an old pocket watch or see what's inside your newer automatic transmission? This, my friends, is where the planet shines: highly efficient at giving large gearing, at high power densities, in a small package when compared to a similar sized set or sets of conventional gears.  BIG tires here we come!

 

Now from above, we know (ignoring a specific gear ratio) that a typical planet is about 1% less efficient than a toploader rockwell. Axle to axle, we see that they are nearly equal.....BUT- the gearing leading up to the axle is where some more losses can occur on a any truck. Once again, on all of our trucks, whether planetary or non-planetary axles, we all run similar transmissions, so let's ignore them. The engine output and tires are usually different, but what if they were the same? Essentially, the large difference in the setups between the planetary truck and the non-planetary will come from the differences in axle gearing which directly coincides with what ratios end up inside the transfer cases in each setup. Now remember from above that, numerically higher gears or ones that give the most mechanical advantage, transmit the most torque, and as such, the faster each gear within the system spins, will see the lowest losses, in a "controlled gearing system" and you'll start to see where this is going. Planets can be more efficeint. 

 

Since, the question was asked about monster trucks, imagine that we're talking about a blown alcohol monster truck on 66's putting out a 1000ftlbs of torque, which is pretty accurate by today's standards, as well as back when they actually ran the 5 ton axles. By ignoring the transmission and making the engine's output and tire size constants in our equations, we can now compare the differences in gearing between the axles and transfer cases in the two setups.

 

In a non-planetary, conventional axled, 5 ton rockwell monster truck that's putting out 1000ftlbs, on 66's with a 7:1(rounded for the example) axle ratio, and 3:1 transfer case will put out 21,000ftlbs to the tires, ignoring frictional losses which we'll get to in a moment.

Math: 1000x7x3=21,000ftlbs

 

In a planetary axled monster truck that's putting out 1000ftlbs, on 66's with a 21:1(rounded for the example with a 6to1 carrier and 3.5to1 planets) axle ratio, and 1:1 transfer case will also put out 21,000ftlbs to the tires, ignoring frictional losses.

Math: 1000x1x21=21,000ftlbs or 1000x1x6x3.5=21,000ftlbs

 

Note that both trucks have the same input power, same overall gearing, the same overall torque output, and you can bet they even have the same wheel speed!!! So much for the planet's killing wheel speed argument.....Don’t believe it? Read on.

 

So what's the difference then if we make all things equal? The difference is WHERE the gearing is located within the overall system and HOW fast the parts of the system are moving.

 

Let's talk torque.

 

After the transmission, the non-planetary 5 ton monster truck is multiplying torque immediately with the 3:1 ratio in the transfer case and has 3000ftlbs going through the lower t-case gear, driveshafts, and pinion, then it gets multiplied again by the 7:1 axle gearing and has 21,000ftlbs going out to the 5 ton axleshafts and hubs! Yikes! No wonder those 3-4ft long shafts pop, even at a 2-1/8" diameter.

Math: 1000x3=3,000ftlbs 3000x7=21,000ftlbs

 

After the transmission, the planetary monster truck isn't multiplying torque immediately with the 1:1 ratio in the transfer case and has 1000ftlbs going through the driveshafts and pinion, then gets multiplied again by the 6:1 carrier gearing and has 6,000ftlbs going out to the axleshafts, and from there goes through the 3.5 planet gears to output 21,000ftlbs to the wheel!

Math: 1000x1=1000ftlbs 1000x6=6000ftlbs 6000x3.5=21,000ftlbs

 

Which drivetrain do you think sees more torque stress throughout the system? The conventional axle system. Plain as day. The driveshafts see greater load and so do more of the axle's components whether under power or landing from a jump.(yes, it works backwards just the same) In a planetary, nearly all of the load is at the wheel end, yet the planetary wins for higher strength "capability" in a more compact design, that's the special "secret" about them. You have a mini-SCS at the wheel end doing most the work so the, "not-so-strong under torque", 3-4ft bar(axle shaft) doesn't have to. Could the axleshafts, gears, and other components become be larger in a conventional axle? Yes, but how big will they need to be? That is the disadvantage, as the planetary can always be designed to do the same or more, yet smaller, about 30-50%, to be exact. This is the number one reason monster trucks made the switch. When they did, they gained about that much extra strength in relatively the same size package as before. 

 

Let's talk speed and losses.

 

For this example let's turn that blown big block to 10,000 rpm and ignore the transmission again or put it in drive(1:1). The non-planetary 5ton monster truck is reducing speed immediately after the transmission in the 3:1 transfer case and has the driveshafts and pinion spinning at 3,333rpm, then it gets reduced again by the 7:1 axle gearing and has the axleshafts, hub, and wheels spinning at 476rpm!

Math: 10,000/3=3,333rpm  3,333/7=476rpm

 

The planetary monster truck isn't reducing speed immediately after the transmission in the 1:1 transfer case and has the driveshafts and pinion, rotating at 10,000rpm! Now we all know what those glowing red rotors are about on Gravedigger or any of the other monster trucks...or all those blown f-106 chunks... Then that gets reduced again by the 6:1 carrier gearing and has the axleshafts spinning at 1,666rpm, and from there goes through the 3.5 planet gears to become further reduced to...you guessed it(or you just cannot believe it)...the same 476rpm to the hubs and wheels!

Math: 10,000/1=10,000rpm 10,000/6=1,666rpm 1,666/3.5=476rpm

 

From above, AND as promised, same overall gearing, the same overall torque output, and the same wheel speed!!!

 

But...Which drivetrain do you think sees more "speed stress" and rpm throughout the system? The planetary axle system. Once again, plain as day. The driveshafts and pinion see approximately three times more speed in a planetary; in this example. In a conventional axle system, the rpm or speed is broken down as it passes through each of the components within the system, whereas with the planetary system waits until well into the axle to reduce system speed. This helps friction efficiency, but stress is high from heat. Here, the conventional axle system wins for reduced stress from rpm and this nets another disadvantage albeit, very small, from a loss through friction. Could the gears become numerically lower in a planetary axle and reduce the speed of the other components? Yes, but at a disadvantage when compared to the conventional axle as the planet by design has more gears and cannot practically go any lower than 3:1 without the danger of becoming weak or a solid axleshaft.  But it's the peripheral speed of the gears that matters with efficiency...

 

Now remember from above that I said numerically higher gears or ones that give the most mechanical advantage, transmit the most torque, and as such, the faster each gear within the system spins, see the lowest losses, in a "controlled gearing system"? Well, when considering a planetary truck and a non-planetary truck's "system", that is, from engine through transmission, through t-case, through axles, to the wheels and not necessarily the axle itself the planet wins because the components spin faster at the same "end" gearing when compared to the conventional axle. We can ignore the engine, transmission, and wheels and tires, as they have been constant throughout my examples. We can even ignore the axles, as we have already seen that the axles are within 1% mechanical efficiency between them, ignoring gearing. Add in gearing and the planet wins because it has more gear and each gear spins faster peripherally.

 

Remember the churning losses and frictional losses? I told you you'd hear about it later. Once again, the planetary axle system wins for reduced losses throughout "the system" due to more mechanical advantage and higher overall speed in the gearing. This transmits more torque, earlier, and further downstream in said system when compared to a conventional axled truck. How? Let's just ignore the axle gearing for now since they are within 1% mechanical efficiency and look at the transfer case. Remember both trucks have the same style, let's say, straight cut SCS spur gears in them with different ratios, so in essence, mechanical efficiency remains relatively constant for high torque and/or speed conditions whereas "total efficiency" is not constant. In other words, with rpm and torque equalized, the gears are at about 99-98% efficient regardless of ratio. If you remember from above, the planetary truck must spin the lower transfer case gear and driveshaft at 10,000rpm, with 1000ftlbs, through 1:1 gearing, at the exact same wheel speed as a conventional axled truck spinning the lower transfer case gear at 3,333rpm with 3000ftlbs, through 3:1 gearing. 

 

Due to this arrangement, slightly better efficiency is obtained via reduced friction through higher peripheral gear speed, earlier within the system. With the spin losses included, "total efficiency" will still decrease from heat with rotational speed and it increases with transmitted torque, but by how much? Well, depending on actual torque and rpm capability it will vary, but remember we limited it at 1000ftlbs and 10,000rpm and at those levels rough estimates are telling me it cannot be over a 3% gain unless 15,000rpm is exceeded or more than 5000ftlbs is coming out of the motor is which isn't possible in a monster truck and even then, it only ramps up to 4% at those levels. Essentially, total efficiency has only dropped from 99-96% to 95-92% and back to 98-95%. This 3% gain, when combined with the 1% loss from a planetary to a toploader is all you'll ever save...which is a 2% gain... Not "a TON" of power lost as you may have been told, Princeton Jake, a measly 2% gain.  Remember there isn't a single type gearset out there that is worse than 90% efficient anyway, at least not one used in a drivetrain, that's why we use them; because gears ARE efficient by design. Now there is also rotational mass, but we can ignore it because of the intensely difficult calculations and weighing of everything, but if I have to explain it more, I'll try. The results may surprise you.

 

This is the final piece of the puzzle in our quest for why the monster trucks switched axle arrangements. Yes, the trucks were going faster and flying higher, but they weren't about to drop power or tire size to keep the trucks going...something was needed that was a substantial increase in strength while at the same time weighing close to or around what they were using without any major disadvantages; the planetary fit the bill perfectly. Naysayers said planetary axles had huge power losses because they had so many gears or so low gears and increased weight and as a result chose not to switch...boy, were they ever wrong. Now, it doesn't take a rocket scientist (or does it?) to see that a 30-50% increase in strength and an increase in total powertrain efficiency substantially outperforms any losses added by a few pounds.  Unless you want me to factor the extra axle weight in...another .02%  

If it was me, I wouldn't be as concerned about axles losses with the intentions of running 66" diameter tires... Why? Spinning weight is not as beneficial as reciprocating weight; that is, weight that must be started and stopped each cycle such as a piston or a transmission part that is stopped and must be brought up to engine speed on a gear change or even a big ass tire. Hmmmn....
As already mentioned, once rotating parts are up to speed it doesn't take a lot of power to keep them rotating. I believe the largest gains would be from lightening the truck and more importantly, the inertia will be that could be reduced by weight savings in the largest of rotating parts...ie big ass tires. Rotating inertia can be greatly reduced by simply removing weight that's farthest from the axis of rotation......25lbs of savings from ditching a 12 in dia planet planet gear assembly won't be worth squat when compared to 25 lbs of savings from a 66" dia tire...

 

 

To recap:

 

Conventional axle system advantages:

  • Less rpm seen throughout ALL components within system=less stress from heat
  • Less power lost in axle system (not through t-case, through axles, to wheels and not necessarily the axle itself)
  • Numerically lower gearing (3:1 or less) can easily be achieved in a conventional axle  
  • Better suited to smaller tires
  • Less stress on bearings

 

Conventional axle system disadvantages:

  • More torque seen throughout ALL components within system
  • Less power capability in TOTAL overall system (through t-case, through axles, to wheels and most importantly the axle shaft itself.)
  • Less strength due to lower torque density at a given size when compared to a planet which could be a problem for larger tires

 

 

Planetary axle system advantages:

  • Less torque seen throughout ALL components within system
  • Less power lost leading up to axle
  • More power capability in TOTAL overall system (through t-case, through axles, to wheels and most importantly in the axle shaft itself)
  • More strength due to higher torque density at a given size when compared to a conventional axle
  • Better suited to larger tires

 

Planetary axle system disadvantages:

  • More rpm seen throughout ALL components within system, not suited for smaller tires 
  • More power lost in TOTAL axle system (not through t-case, and not necessarily the axle itself)
  • Gearing numerically lower than 3:1 is not practical due to inherent design and becomes geometrically impossible at 2:1
  • Higher bearing loads 
  • Higher heat generated

There it is folks...numbers and facts...now you can tell people what you've learned. Not because that's what you "heard", because that's what you know. 

 

Class dismissed....for now....bîtches!

 

 


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Quote:
Originally Posted by iniviate
Who on 72"+ tires can do better than that?
Quote:
Originally Posted by z71on46s
I will monster truck your shit!
Quote:
Originally Posted by adamsnotsoperformance
oops read that backwards.
Quote:
Originally Posted by damnyankee
I've built everything on mine and you make me want to throw rocks at it.
Quote:
Originally Posted by ON TIME
SHUT THE F#CK UP CORKY!
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