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16 comments
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Driveshaft Guard

05/09/2013 6:50 PM

Hi,

I need to design a class 8 driveshaft guard. On our Hydrovac truck, we run a driveshaft from our transfer case (or split shaft pto if you like) to a blower.

The driveshaft will turn at max 2500 rpm, and will be max 6 feet long.

I need help to calculate the forces involved in a yoke failure, and what would be required to restrain that force from damaging people and equipment.

Worst case we would use the SPL 250 shafting, but mostly we are lighter than that.

Our typical drive angle is 3 degrees or less, and approximately 60 inches.

I'm not an engineer.. and any guidance on this is appreciated.

Thanks,

Chris

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Pathfinder Tags: calculation drive shaft momentum
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#1

Re: Driveshaft Guard

05/09/2013 7:15 PM

Something like this?

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#8
In reply to #1

Re: Driveshaft Guard

05/10/2013 9:12 AM

didn't know they existed, and will certainly look into it for applicability.

Thank you so much. great find!!

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#16
In reply to #1

Re: Driveshaft Guard

05/11/2013 10:40 AM

Looked into these... and not what we need primarily. While our first objective is to protect people, and this is appropriate for that. The original problem is about driveshafts flying apart at speed, and one even bent the chassis. This is a class 8 truck triaxle, with double wall frame. Extreme forces, and a level above agro. I suspect we will have to fab our own, but just how strong does it need to be. I nedd the basic math for the dynamics, or a link to software that calcs dymamics... We have a very good shaft provider, and thay say they hsve no product that can do this of the shelf. Chris

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#2

Re: Driveshaft Guard

05/09/2013 7:34 PM

are you planning on using carrier bearings to guide the shaft as well or are you simply looking for a loop that covers the shaft?

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#6
In reply to #2

Re: Driveshaft Guard

05/10/2013 7:39 AM

carrier bearing example

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#7
In reply to #6

Re: Driveshaft Guard

05/10/2013 9:11 AM

there is a 'steady bearing' that comes installed with the shaft system from the factory.

on the lower driveshaft, but that is something I didn't think about for the upper driveshaft that we install (and are needing to protect) because we could have steady bearings installed. good idea!

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#3

Re: Driveshaft Guard

05/09/2013 7:45 PM

you might want to utilize a carrier bearing design that not only will stabilize your shaft but also acts like the guard you want. why be redundant when you don't have to be?

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#4

Re: Driveshaft Guard

05/09/2013 9:03 PM

Long time no see Chris. How's life?

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#9
In reply to #4

Re: Driveshaft Guard

05/10/2013 9:14 AM

super busy... I've not been on here much for over a year now... have a great job of course. I get to invent and design stuff all day long... but it is overwhelming at times.

a granddad again. (2nd... boy... etc)

thank you for asking.

how are you?

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#12
In reply to #9

Re: Driveshaft Guard

05/11/2013 8:46 AM

Good. Moving into the next chapter with a patent and web based business. Failure is not an option.

Glad to hear you're busy...beats the hell out of having endless time on your hands.

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#5

Re: Driveshaft Guard

05/09/2013 10:42 PM

NHRA (and other racing venues, I expect) require drive shaft loops. You can Google 'drive shaft loop' and see many varieties. Here's a link to a common bolt-on style: http://www.jegs.com/p/Jegster/Jegster-Universal-Bolt-On-Driveshaft-Loop/744057/10002/-1 . They are required to be no further than 6" from the U-joint. They aren't required to be round loops, but if you ever need one, you'll wish it was round! You can Google 'NHRA drive shaft loop' to get the installation rules, if you want. NHRA is mostly concerned with preventing the car from 'pole vaulting' on the drive shaft if the front joint breaks, and many classes don't require a rear loop, I think. But a lot of guys install a rear one to minimize damage to the floor pan if the rear joint lets go.

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#10
In reply to #5

Re: Driveshaft Guard

05/10/2013 9:15 AM

thank you!

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#11

Re: Driveshaft Guard

05/11/2013 6:18 AM

go to any good farm store and you should be able to buy a shaft guard right off the shelf. Farmers use them all of the time (or should be) on PTO's.

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#13

Re: Drive shaft Guard

05/11/2013 9:45 AM

In addition to the other suggestions, try the folks who make school busses. I think they are required there also. I don't know what all goes into the design, but many vehicles should have them.

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#14

Re: Driveshaft Guard

05/11/2013 10:13 AM

There is more than one way to skin a cat. In this non-automotive application needing a few hp you might consider a closed loop hydraulic solution. The pump is driven by the tractor, the motor is attached to the blower. Properly sizing them, the tractor might be running near idle.

No flying parts possible, nor any snagging.

When you do not need it, detach the pump from the tractor, and store it in the garage.

Since this does not need the big chassis to mount on, I am not convinced, that this is any more expensive, either.

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#15
In reply to #14

Re: Driveshaft Guard

05/11/2013 10:31 AM

We did consider hydraulic, but ruled it out. Good thinking though.

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bigg (1); chrisg288 (6); fixitorelse (1); Fredski (3); kramarat (2); Lehman57 (1); leveles (1); SolarEagle (1)

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