Archive through July 28, 2017

[wcompton]

James-
Tip speed. (just the tip) The pulley ratio is set so that blade tips move at the same speed, so smaller blades turn faster. Vice versa for large blades.

 

[hydroharry]

Wyatt - wait a minute - what you said doesn't make sense. Could you re-read your post and clarify please.

 

[kide]

Makes sense to me.. Think tip travel in feet per minute. The smaller diameter circle the tip of the shorter blades makes requires more revolutions per minute to travel the same distance as the tips of the longer blades. If you don't have same tip speeds, the cut will be uneven, especially as the blades dull..

 

[hydroharry]

Gerry - ok, now I get it. You said "tip travel in feet per minute". Wyatt only mentioned tip speed so I was thinking rpm's and how could the smaller ones turn faster if they are turning at the same speed - it just didn't make sense until you added "distance", as in feet per minute for speed.

Most of the time our discussions about blade speed is speeding them up. I know the Assoc. of Power Equipment Manufacturers changed their safety spec to slow blades down sometime back in the mid 70's - and that's when IH changed the center pulley on the 44" and I believe 50" decks - and why people always want the earlier pulley to speed the blades back up.

 

[wcompton]

Dusting off my old Ag Engineering hat from ISU, if I remember correctly- tip speed as it would apply to rotary cutting as well as cutter bars sort of hit a wall at a particular speed (something around 280 FPS, don't quote my bad memory) where the cutting edge is moving fast enough that it pushes over the plant rather than cutting it. With the aide of air movement (like in a mower deck) you can cheat this a little, BUT you run right up against material limits of the steel blade and whatever the consumer does with it. OPEI went above ASAE as a matter of consumer safety (non-farm users & users of walk-behind equipment) and put blade tip speed limits and RPM limits in effect.

 

[stanner]

this does apply to the on topic conversation below.....

 

[gloughery]

Two problems. (1) I still have trouble getting my brakes right. Yes, I will clean them all up (over the winter) but it seems to be the caliper spacer (part #7) inside the spring is too long. It causes too much space on each side of the, uh, axle disc. I don't have the patience to re-shoe these, can someone refer me to somewhere who does a good cost-effective job? (2) What kind of gasket material works best when putting (Bargman) rear lights back on a fender?
And BTW, I went with the V61's based on Marty's photos back on July 20th, thanks Marty.

 

[wshytle]

George-

I order a medium grade friction material from McMaster-Carr. It comes in 7-1/2"x7-1,2" sheets among other sizes but this the size I get. I also get the 3/16" thick material and have to shave it down a tad in order to fit the rotor. I use JB Weld for the adhesive and it has worked fine.

.

 

[kmcconaughey]

George, to add to what Wayne wrote, there's this:

Brake Relining

 

[jstouffer]

Thanks Wyatt,Harry, and Gerry for all your comments when you describe it as tip speed I now understand the difference. Much appreciated everyone.