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# Info Letter No. 90 - March/April 2005

#### by Fritz Ruoss

Submenus for xy plane, xz plane and resulting curve for diagrams ease faster access and clear structure.

Life expectation of low loaded roller bearings is displayed with decimal exponents now.

ZAR2 - Menu Structure and Production Drawings

New structure with submenus at "View" and "CAD" menu. Production drawing of pinion and bevel wheel together on one screen.

ZAR3 - Comfortable Input Windows

Former input window "Strength" has been split into "Power" and "Application".

At "Edit->Power" you can choose to input a combination of speed, torque and power for worm or worm wheel.

ZAR3 - Strength Calculation according to DIN 3996

ZAR3 calculates safety factors according to Niemann. Calculation according to DIN 3996 has been added now. If you enable DIN 3996 calculation, you have to enter some additional factors:

• Roughness worm Ra1
• Lubrication type
• Wheel mass temperature thetaM
• Dynamic oil viscosity eta 0M
• material lubrication factor WML
• bedding
• shear fatigue strength tau FlimT
• material factor YW

Other coefficients are defined in tables. Unfortunately, DIN 3996 offers table values for worm material 16 MnCr5 and worm wheel materials GZ-CuSn12, GZ-CuSn12Ni, GZ-CuAl10Ni, GGG-40 and GG-25 only.

Additionally, there seem to be some errors in DIN 3996 (efficiency calculation):

Pvz = 0.1*T2*n1/u * (1/eta_z - 1)

More simple: Pvz = P2 * (1 / eta_z - 1)

But correct: Pv = P2 * (1 / eta_tot - 1) mit Pv = Pvz + Pvo + PvLD + PvD and

eta_tot = eta_z * eta_0 * eta_LD * eta_D

Additionally, DIN 3996 rounds "2 * PI / 60" to "0.1" (5% difference).

FED12 - New Materials

Three FIBROFLEX materials (80, 90 and 95 Shore A) for elastomere springs have been added to the material database of FED12.

FED12- E-k Diagram

Values of form factor k as function of spring travel are listed in E-k diagram now.

ZAR4 - Transmission Ratio

Until now, number of teeth were equal for gear 1 and gear 2 (total transmission ratio = 1). Now you can enter a total transmission ratio (integer value).

Database Problem for Drive Size > 1 TB

Error 227 (not enough space) occurred, if more than 1000 GB space is available on database directory and temporary directory. Please configure a smaller drive for database directory and temporary directory for now, we will fix the problem with the next versions.

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