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JonetteP

BVB horsepower rating

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JonetteP
this has came up in dicussion before as being the weak point in the simpicity and allis chalmers units. Here is the question, can you pump 25 hp through the BVB using synthetic oil. The idea of a 25 hp unit with pressure lube is awesome. Can the unit stand up? I know the bvb was a weak point in these 30 plus year old units, but I think with the newer, smoother engines, the bvb would do fine. Can you imagine a 7117 sith a 48" inch deck, No power problems involved. Thank You for your input!

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Woodydel
Belts will slip when you have exceeded their capability to grab the pulley. The engineer has already computed the amount of "grip" the belt needs to transmit the power from the engine. That "grip" is predetermined with the spring tension he designed into the mechanism. When you exceed the limits of "grip" the engineer has designed into the pulley system the belt should slip. If you have the tension too high on the belt it is possible for the belt to break. Aftermarket belts will do this. Tractors will usually lose grip at the tires before the "grip" of the belt has been reached. The engineer uses belts on Simplicity tractors because they feel you can ride the clutch and allow the belt to slip in varying situations and Simplicity makes note of this in their literature. They are of the opinion that if you have a clutch and it is ridden the clutch material will overheat and fail. A belt being ridden does not overheat at all, it just "slips". To further prove my point that the idler is the determining factor in the amount of "grip" a belt will exert take a look at an exerpt from their repair manual. I did not bother to take the time to find a reference to the BGB but the concept is exactly the same. Once you exceed the idler's tension the belt will slip. Excessive horsepower as in a larger engine than what the engineer has anticipated will cause the belt to slip if it is adjusted to specifications....Woody http://image.photoloft.com/opx-bin/OpxFIDISA.dll?src=/PhotoLoft/Asset19/2002/03/06/9084/9084550_0_4864.fpx,0,0,1,1,512,493,FFFFFF

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Dutch
Neal, When I first got involved in these tractors just a couple of years ago (seems longer than that), there was a discussion on the BGB. The old timers seemed to believe the "chatter" of tilling was the biggest enemy of the BGB. That makes sense to me. Using "common sense engineering", I would suspect that RPM would also effect the BGB. But, 3000 RPM is the same whether coming from a 12hp engine or a 25hp engine. At 3000 RPM, the load placed on the BGB would seem to make the only difference. If a 48" deck can mow grass with a 12hp engine, I can't see where 25hp would make any difference. In fact, the smoother power flow from a V-twin may be easier on the BGB than the "pulsing" power from a 12hp single. The only problem I can see is the temptation to push the machine to use all of that 25hp. Let's see if others agree.

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Dutch
Problem is, with few exceptions, tractors with a BGB don't have a separate front PTO clutch. The center PTO clutch on the BGB works just fine as designed. Just like anything else, if you redesign an attachment or increase engine size, make sure you plan and use carefully.

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PatRarick
I would agree with Dutch, to a point. With a 25hp engine, you wouldn't notice the engine lugging in heavy mowing as much as you would with a 12hp. I would think that you would "unknowingly" overload the gearbox. While I agree that tilling is the hardest on the gearbox, a local Simplicity dealer disagrees. I don't know why, but he claims that the BVB driven snowblowers are much harder ton the BVB than the tiller is. Maybe it's just a matter of opinion. Pat

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StinKy
I agree with Dutch, but check out mess. #4730 and MikeES reply to it. I gather from what he says the axle tube is likely to give up before the BGB. Having had a cracked axle on a lowly 9 hp rig and the BGB surviving in good shape I think at least in heavy pulling situations the axle is the weak link. Note he also says 40 hp. is around max. A puller type guy should know cause he's probably busted enough of them!!! Ha Ha! Dick

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Dutch
Pat, I think we agree. Like I stated, “The only problem I can see is the temptation to push the machine to use all of that 25hp.” I would also agree with the snowthrower being harder on the BGB than a tiller. Assuming the tiller is used properly (small bites in moist, rock free soil), except for some “chatter”, it should place less of a load of the BGB than the constant load placed on it by an auger full of heavy wet snow. Al Eden noted, snowthrowers powered from the BGB have one of the PTO idler pulleys moved to the tractor frame. I would assume this harmlessly absorbs some of the load. I think I unintentionally achieved the same benefit with my “Hybrid Hitch”, which is mounted to the frame between the snowthrower and BGB. Dick, The tractor pullers push to the limit, sometimes beyond (that’s their sport). I believe most broken axles are caused from increasing traction so the tires don’t slip. IMO, wheel weights just amplify the problem with sudden starts or stops. Woody, When is a belt supposed to slip? I built a roller that probably weighs over 2000 lbs. When going up a hill with my 18hp, I suddenly lost all power. I thought the BGB or hydrostat blew, but the hydro pump belt had snapped. I replaced the belt (with OEM) and after 3 runs up the hill, it snapped again.

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Dutch
Marty, I built the roller for blacktop (actually millings & RAP). I usually pull it with a truck or larger tractor. I used it on the lawn last year because the moles (voles?) were really frustrating me. Only thing I accomplished was snapping a couple of belts. For now the moles have won. They can have the lawn. Stopped feeding my lazy male cats, and they must have found new homes. Got a real pretty female now. She brings moles home even after I feed her. She's pregnant. Hope she has a whole bunch of little mole catchers.

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Woodydel
These BGB's are lasting 30-40 years so they are not a weak link...Everything is overbuilt and many parts are the same since the first day they were designed except for minor changes...The gear transmissions are the same since the beginning on all of my tractors according to Simplicity..If it ain't broke don't fix it..As the power of the machines increased the parts remained mostly the same so a few more horsepower probably won't do much to their design..

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MikeES
Here is my nickels worth. As a puller, I don't think you can harm the BGB, we have made hamburger of the differential, we have turn an axle tube into a corkscrew, we have sheared keys in the transaxle, but we have never even blown an oil seal in the BGB (even turning it at 5000rpm +). I have blown a BGB, but that was on my HB212 that had done a lot of hours of "hard" tilling. IMO the tiller is the hardest thing on the BGB. Now that my yard has been landscaped, and we only till the garden (soft soil) my HB212 BGB is still like new 15 years after the rebuild. Mike S.

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