Merseburg wheel part

[barksalot]

What is this part? Do not remember it being discussed before.

[ovyyus]

Its the handle for stopping the wheel.

The next question is interesting: How much force needs to be applied to the handle in order to stop the wheel?

[barksalot]

I thought the part about a person being lifted off the ground a little when stopping the wheel was from the rim area, but can really envision it now, thinking maybe it was from that handle.

If it was the rim area that it was being stopped from when that happened, then doing it from that handle could be very hard or even dangerous.

[ovyyus]

Wagner claimed the wheel was stopped easily by Bessler's skinny assistant grabbing hold of the axle. I assume he meant the axle handle. If the wheel could lift 70lbs directly from its axle while rotating at over 40 RPM as claimed then how could it be stopped easily by someone grabbing hold of the handle?

If the unloaded wheel rotated at 50 RPM then the constant braking force required at the handle to bring it to 40 RPM would be about 18lbs (based on depicted handle length and a claimed 70lb axle lift force). To bring the wheel to a complete stop would require much more force at the handle for a longer period of time. That doesn't sound easy at all.

At these required force levels the handle seems both dangerous and impractical for stopping the wheel. Perhaps Bessler's claim of 70lbs lifted directly from the axle is wrong?

[jim_mich]

Or perhaps Wagner was wrong or exaggerating facts to suit his own agenda. Bessler maintained that Wagner was a liar.

[ovyyus]

Perhaps Jim, but that still does not readily explain safe use of the depicted axle handle given the claimed lifting capabilities of the wheel. If grabbing hold of the turning wheel at the rim might lift a man off the ground then grabbing hold of the axle handle would throw him across the room, or rip off his arm! Something does not seem right.

[jim_mich]

The same energy is required to stop the wheel, whether it is applied to the axle handle or to the rim. Force times distance would be the same. A much greater force but at a much slower speed needs to be applied to the axle handle, while a much weaker force but moving at a much faster speed needs to be applied to the rim. The energy needed to stop the wheel is the same in either case.

The assistant would much more likely be lifted by the handle than by the rim.

[justsomeone]

Could this part have been a rope stop to keep the rope away from the wheel?

[ovyyus]

Jim, energy becomes irrelevant when leverage force exceeds the operators capability.

Justsomeone, we don't have to guess what it is because Bessler tells us its a handle.

[ovyyus]

Wolff reported the lifting of the load of 6 whole bricks (70 lbs) as being quite slow due to a 4 x pulley reduction (see attached 4 x pulley reduction diagram).

Weisse reported that wheel speed was the same whether lifting or lowering the 70 lb load. The similar lifting/lowering speed might be consistent with the relatively light loading due to a 4 x pulley reduction lift.

The depicted handle size and its practical applied stopping force also appears more consistent with a 4 x pulley reduction lift wheel torque.

A picture emerges of a wheel that was intended to demonstrate the practical application of lifting a box of 6 bricks to the height of 1 storey (standard building practice lift at the time). In order to demonstrate this standard lift Bessler was forced to employ a 4 x reduction pulley due to the wheels limited available torque. This means that the wheel was not capable of lifting 70 lbs directly from its 6 inch axle. Furthermore, this conclusion helps explain the practical and safe use of the depicted axle handle where the required breaking force applied to the handle would be no more than a few pounds in order to stop the wheel. Of course that would also mean the wheel was actually 4 x less powerful than its marketing campaign might have us believe.

[barksalot]

I wonder if the handle was also the point that the wheel was started from.

In particular the reference about just a few fingers were needed to get it started. This would suggest to me that the wheel was of a much lighter construction than I had imagined.

Did I remember that correctly about a few fingers?

[rasselasss]

I agree with JSO,definitely a rope stop or guide.

[barksalot]

I think Bill is right on this.

Initially I thought the same thing but realized a rope stop would most likely be on the other side of the rope because that is where the stationary support post is.
Because the wheel and axle move in unison no need there, but the stationary support side would probably be a more likely spot for one to prevent the rope from rubbing on it.

[rasselasss]

Barksalot,the reason,if you look at the full image of the wheel mechanism,the rope hits the axle at an angle and without a stop or guide it would wind its way to "bunch "at the wheel centre when winding the load upwards...when its lowering it would'nt come into play....just my reckoning......also a short "tommy bar"turning at 26-50 rpm would be near impossible to grab ,let alone stop a heavy wheel turning ,it would more than likely cause personal injury in the process of trying ....Good Luck.

[ovyyus]

In the official Certificate issued for the Merseburg wheel test it is stated,

The machine was started by a very light push with just two fingers and accelerated as soon as one of the weights, hidden inside, bagan to fall. Within about one revolution, the machine had aquired a strong and even rotation, even when a box was lifted, which had been filled with six whole bricks weighing together about seventy pounds.

If a 70lb weight was actually lifted directly from the 6 inch axle while the wheel accelerated to more than 40 RPM in 1 rotation then it might be fair to conclude that a breaking force of 70lbs would need to be applied to the 6 inch axle in order to bring the loaded wheel to a stop in 1 revolution. That would translate to an applied constant breaking force on the handle of about 20 lbs for 1 whole wheel revolution in order to stop the already loaded wheel. The required breaking force to stop the wheel in 1 revolution if it was not loaded would seem unreasonable! In light of Merseburg Wheel drawing item #23, "handle to stop the wheel", the 4 x lift reduction reported by Wolff seems to make much more sense.