# B&S 49-series (810cm3/49ci) for aircraft use - TiPi's Q&A thread

Discussion in 'Firewall Forward / Props / Fuel system' started by TiPi, Oct 4, 2019.

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1. Oct 13, 2019

### karmarepair

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I have query in to Universal Hovercraft about the OEM for the Taperlock bushings. These couplings are pretty generic in the US, although "Taper-Lock" is a Gates trademark; here is a data sheet on one manufacturer's "P1" size coupling with an 1-1/8" finished bore that looks like what Universal has on offer https://www.bbman.com/catalog/product/P1x1-1_8
Torque Capacity (lb/in) 192

2. Oct 13, 2019

### TiPi

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not sure if these specs are correct, torque is only 22Nm (1/3 of the actual engine torque), material is steel and Al usually has lower values due the the lower tension/compression values.
The "Taper Lock" name is the system of bushes with matching pulleys, gears etc, not the style that Hovercraft calls taper lock. The 1610 bush is very marginal for torque transmission, slip torque on a 28mm shaft is only about 170Nm with no key. With key, the value is higher but Fenner refers to their tech department as the slip will then be at the taper interface.

3. Oct 13, 2019

### pictsidhe

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Taper-Lock was originally a Dodge manufacturing trademark, now with Baldor Electric. Gates uses it with permission.
I looked at using higher clamping force with the taper locks, but it's marginal. Torque capacity needs to be much higher than output torque if the prop is now the flywheel. One book that I have suggests a figure of 7x. The key has very limited torque capacity, They are usually a fairly soft iron, so not highly abuseable.

4. Oct 13, 2019

### karmarepair

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They taught me at engineering school never to rely on the key.

The P1 size taperlocks sold by Universal SEEM inadequate, UNLESS that spec is wrong, and those values are ft-lbs? Even the larger B&B Q and R sizes only go up to about 350 ft-in = 29 N-M. BUT I've seen these values described as "Wrench Torque", which to me indicates the installation torque on the cap screws, and NOT the carrying capacity of the coupling. Hmmmm.....

Still looking for better data...the slightly different QD taper bushings have torque capacities from 3500 inch-lbs for the smallest available in stock for an 1-1/8"/28mm shaft ("SH"), all the way up to 30,000 in-lbs for the largest for that shaft size ("F") http://www.regalpts.com/ImagesPower...owning-Q-D-Bushings/Browning Q-D Bushings.png
400 N-M = 3540.3 so a style QD, size "SD" or "SDS" should work, and the "grip length" (E on the data sheet) is .88" to 1.38". Back converting to the P1 split taper bushing, it has a grip length of 1-5/8 inches (1.625"=41.275mm). I'm beginning to believe they might work....interpolating in the QD tables, their capacity MAY be as high as 12,000 in-lbs = 1355.82 N-M. I've made inquiries to Regal for better engineering data.

The Tsubaki web site is NICE. I particularly like their AD-N bushes. https://tt-net.tsubakimoto.co.jp/tecs/pdct/kpl/pdct_Dtl_PL-ADN.asp?kata=PL028X055AD-N LOTS of length, and TWO tapers. MORE than enough capacity. Fits in a straight bore. I've made inquiries to a US distributor about price. I could not get the Fenner site to work at all.

And as near as I can see, the Universal bits use a STEEL bushing in an Aluminum hub. I'd love to be able to use them, as they are cheap and readily available.

I like what you're doing with the B&S 49 series, but I'm actually thinking more about a Kohler Command Pro 752 or 940 horizontal shaft conversion, with MINIMAL modification - heads up, direct drive. Universal hub off the PTO end, lighten the flywheel up.

5. Oct 15, 2019

### karmarepair

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Still on the Universal Hovercraft bits...the type of bushing they use is called a Browning Split Taper Bushing. Browning was a major OEM of drive components, and now is part of Regal-Beloit - which you would think would be in Wisconsin. Nope. The Philippines. Some back and forth:

Ryan Young
Sub: Torque capacity of q2 split taper bushing on 1-1/8 inch shaft
To: ApplicationEngineering.PTSolutions@regalbeloit.com

Your specifications list “wrench torque” but not actual capacity.
Could I get the same data for the P1, P2, Q1, same bore diameter?

Hi,
Information is proprietary.
Thanks,

400 N-M. What is the smallest coupling that can handle that level of torque on a 1-1/8” shaft?
I’d LIKE to use the P1, if it can handle that level of torque.

P1, P2 and Q1 can handle the 400N-m (3540 in-lbs) torque capacity.

Regards,

Thanks,

ROMYSAN IRIS DELA CRUZ
I find this oddly unsatisfying, although I'm not completely sure why. Why is this WORSE than the numbers listed in the Tsubaki web page? I guess since I can't see the TRENDS. How MUCH more than the asked for torque will the P1 reliably transmit?

Vigilant1 likes this.
6. Oct 15, 2019

### TiPi

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Thanks for that. I'm always a bit hesitant with companies that are not publishing their engineering data.
I have a Tsubaki AD-N lock already, unfortunatley they only come in metric (28mm) so I will have to machine the PTO end of the crank if I use this one. Still going back and forth on the alternator (flywheel or PTO end) that will dictate the final design of the prop hub and shaft interface. The transmissible torque is 755Nm, so well above what I need.

7. Oct 16, 2019

### Vigilant1

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FWIW: US parts house McMaster-Carr carries a wide variety of taperlocks in SAE/Imperial sizes. There are dimensions, drawings, and prices are at the link, but no ultimate torque values. It is possible the ultimate source for these is the same company karmarepair is talking to in the Philippines.

I'm guessing you've rejected the idea of using shrink fit prop hub? Nobody likes the "excitement" of assembling them, nor the "hope you like it, because getting it off will be a dicey proposition" aspect. But, it is a single piece, light, and typical users would have little need to remove them during the life of the engine. I haven't done the math regarding the B&S shaft and potential hub torsional capacities, as you may have already rejected the idea for other reasons (but did find a nice calculator). Shrink fit prop hubs have given good service on VW aero engines (2 cyl and 4) of stock stroke, but not the larger engines (in fairness, IIRC, the shrink fit hubs stayed firmly attached even with the larger engines, the problem was the crank.). Obviously, the torque pattern of the B&S V-twins and the crank stub dimensions will different from the VW.
VW Shrink fit hub listing at Great Plains Aircraft Supply (bottom of page)

Shrink Fit hub installation instructions

Last edited: Oct 16, 2019
8. Oct 16, 2019

### TiPi

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It has crassed my ming for a few seconds. Cons are:
Precision of machining required (shaft and hub)
Unlike a VW, the Briggs can't be disasembled with the prop hub on the PTO shaft

As this is still an experimental engine, I expect an internal inspection, modification or repair to occur a few times in it's early life. The shrink-fit hub would make this too difficult as it can't be fitted until the engine is assembled and needs to be removed prior to disassembly.

9. Oct 16, 2019

### BBerson

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Maybe a tapered adapter could be fitted with a shrink fit on the 1/1/8" shaft. The hub would have a matching taper and the hub could be removed and the tapered adapter would remain.

10. Oct 17, 2019

### TiPi

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Good thinking! A permanently installed taper that is a tad smaller than the bearing dia (41.36mm / 1.625"). Have to think about that design

11. Oct 17, 2019

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