Provide more detail on how you arrived at 6 and 3. Where on the shaft did you determine these values?

Provide the steel's physical strength properties for each:

State your units. english or metric

Properties ............................... 4140 ................. CK45

1. ultimate tensile................ .............

2. yield................................. .............

3. endurance....................... ............

4. operating temperature range

Provide your applied loads and the following:

1. Is the pulley a driven assembly? If so provide the T1; T2 values

2. Need to determine the mean and alternating stress

3. Fit the data to a Goodman Diagram

4. Vector angle of T1; T2

5. Shaft turndown ratio and surface finish

With these and the pulleys shaft, end disk and shell dimensions, a precise number can be determined. ■

According to my book Ck45 is a straight carbon/manganese steel that may be hardened nd tempered, while 42CrMo4 is an alloy steel ".. for hardening and tempering." While the carbon content is similar the ruling sections will be markedly different.

So what is the heat treatment condition of the two steels? ■

Samim..

Whatever you do, don't forget the deflection criteria as well.

Limit the shaft deflection to 5 minutes.

Cheers

LSL Tekpro ■

So it's probably a waste of money to have a high strength alloy steel. ■

Thanks Designer.. Thats indeed often the case.

What Anglo American found some time back, was that fancy steels were too fussy with regard to NDT and quality control, so they opted for En3A for non drive pulleys and En8 for drive pulleys, and limited the stress to about 65Mpa and deflection to 5 mins.

Cheers

LSL Tekpro ■

Graham,

I think I've said this before about shafts -

Chain conveyors EN24T

Belt conveyors EN8 ■

You guys, with the unusual designations, should offer the following for others to understand the comments. Either in mPa or psi are OK:

1. tensile strength

2. yield strength

3. endurance strength

Then we can all participate without need to Google.

Bye-the-bye what does the shafts rotation (<5 min.), at the end disk crossectional centerline, have to do with the design of the shaft? Any pulley designer will tell you, you also need to know the stiffness ratios of the shell, end disk and locking device together with the shaft dimensions between the end disk centers as they contribute to the shaft's fatigue stress at the locking device outer shoulder.

The 5 min. criteria has contributed to a number of pulley failures when a designer also made the end disk excessively stiff and the locking device too flexible such as the Rfn 7012 series on bigger shaft pulleys. Modern treatment evaluates the locking device outer shoulder fluctuating stress and its mean stress to see if it exceeds the shafts stress endurance limit.

A stronger rated steel can survive where the low value C1042-1045 steels cannot as Axel points out. A more flexible end disk can provide improved shaft stresses to acceptable levels. ■

But I'll have to Google for "C1042" and "C1045" for tensile strength, yield strength, endurance strength. ;-) (still, I suppose that's my problem for being a Brit) ■

Precisely the point. Call it by any name, but the facts will tell the game. ■

For one of our clients in UAE we need second grade Gypsum sheets or Cement sheets in large quantities to be used in Labour Camps.

Anil

9811055650 ■

CEMA or RULEMECA,

They do not consider the stiffness constants of shaft, locking device, end disk or shell contributions to stress at edge of locking device and therefore ignore a critical point of failure.

They do not apply the work of Peterson's stress concentration factors at the turndown radius from hub diameter to bearing diameter.

On small shaft diameters, this may be OK for good guess work, on larger shafts this is an engineering omission. ■

Whatever is written in this book, or that book you need to understand the theory and, more importantly, if it relates to the current state of knowledge in the industry.

Just because it's written in a CEMA (or any other) publication is not a guarantee it's right. ■