Deck pulley size change effect?
 

Long story short (save the full report for later), I put a 38C deck on my 1450.

I used the pulley from the 50A, which is 2 inches smaller in diameter (38C is 7", 50A is 5"), but the spindle drive pulley is also 2" smaller (6.5 vs 5.5). What is the effect of this? The driven (deck pulley) getting smaller will speed it up, but the drive (spindle drive pulley) is smaller, slowing it down......does it cancel out? :bigthink:

Thanks,
Mike

Without actually doing the math, the changes you made should make the center spindle turn much faster but the outer spindles will be about the same as they were before.

That's what I am thinking. I will try to find some time today to work the numbers. Think it will have a negative effect mowing?

I did the math, but did not have the exact size of the PTO pulley (I used 6") or outside spindle pulleys (I used 5"), so this is not true RPM numbers but a representation of what is going on.

Before:
PTO- 1000 RPM, deck drive pulley - 857 RPM, outside spindles - 1114 RPM

After
PTO- 1000 RPM, deck drive pulley - 1200 RPM, outside spindles - 1080 RPM

So based on that, the middle spindle gains 343 RPM, or 5.71 RPS, or 70%!, the outside spindles spin 34 RPM, or .6 RPS slower, or 3%.

I will try again with the real PTO and spindle pulley sizes, but the percentage should be close.

I doubt the two little blades will be overly effected, but that large blade will be humming!

so the precentages are almost balls on with the right pulley sizes, the rpm changed a little thats all....