In my simpleminded way I tend to trust in what I can see measure touch count taste and smell above opinions – so here goes - VCU OWUT (One Wheel Up Test)and Bells Youtube Test – a comparison.
Just watched Bells test video to take a stab at the time for from horizontal to 45degrees. Thats comparable to the OWUP in as much as it is not an absolutely constant torque applied but the method is the same.
I guessed about 3 secs for the Bell test from horizontal to 45degrees – that’s 360/45 x 3secs for a rev = 24secs = 60/24 = 2.5rpm slippage.
Torque applied was 7kg x 0.78m = 5.46 metre kilograms
On a OWUT the torque on the VCU is reduced by (ignoring friction) by the CW/Pinion gearing and doubled by the Diff gearing as the other wheel is static.
So to get 5.46 Metre Kilograms you need 5.46 x 45/14 x ½ = 8.78 Metre Kilograms
and using a 1.2 metre bar that’s 7.3kg weight.
Going back to Bells slippage speed of 2.5 rpm at the vcu to achieve that on a OWUT you need to drive the wheel at 2.5 x14/45 x 2 = 1.56rpm – for 45 degrees that’s 45/360 x 1.56 x 60secs = 11.7 secs.
Surprise surprise!! – given that I ignored friction and there WILL be some and I guessed Bell’s 3 seconds - I find my trucks time of 12secs and my Daughters 10k old new GKN VCU’s time of 11secs using an 8KG load very comparable – that’s only a 10% difference in weight to achieve the same slippage speed.
Hippo’s graph back in 2012 needed 10kg to achieve 12 seconds – a little stiffer than ours but generally believed to be still very useable.
So – The OWUT at 8kg and Bell’s rig are to all intents and purposes comparable
That’s not opinion – just arithmetic.
I’ll get me coat.
Just watched Bells test video to take a stab at the time for from horizontal to 45degrees. Thats comparable to the OWUP in as much as it is not an absolutely constant torque applied but the method is the same.
I guessed about 3 secs for the Bell test from horizontal to 45degrees – that’s 360/45 x 3secs for a rev = 24secs = 60/24 = 2.5rpm slippage.
Torque applied was 7kg x 0.78m = 5.46 metre kilograms
On a OWUT the torque on the VCU is reduced by (ignoring friction) by the CW/Pinion gearing and doubled by the Diff gearing as the other wheel is static.
So to get 5.46 Metre Kilograms you need 5.46 x 45/14 x ½ = 8.78 Metre Kilograms
and using a 1.2 metre bar that’s 7.3kg weight.
Going back to Bells slippage speed of 2.5 rpm at the vcu to achieve that on a OWUT you need to drive the wheel at 2.5 x14/45 x 2 = 1.56rpm – for 45 degrees that’s 45/360 x 1.56 x 60secs = 11.7 secs.
Surprise surprise!! – given that I ignored friction and there WILL be some and I guessed Bell’s 3 seconds - I find my trucks time of 12secs and my Daughters 10k old new GKN VCU’s time of 11secs using an 8KG load very comparable – that’s only a 10% difference in weight to achieve the same slippage speed.
Hippo’s graph back in 2012 needed 10kg to achieve 12 seconds – a little stiffer than ours but generally believed to be still very useable.
So – The OWUT at 8kg and Bell’s rig are to all intents and purposes comparable
That’s not opinion – just arithmetic.
I’ll get me coat.