Overhung (Fr) & Thrust (Fa) Loads

Overhung (Fr) & Thrust (Fa) Loads

The permissible overhung loads (Fr) and thrust loads (Fa) for the individual gear boxes must also be taken into consideration when selecting a gear box.

If overhung loads (Fr) are encountered together with thrust loads (Fa), the overhung load (Fr) is reduced by the value of the thrust load (Fa).

Overhung & Thrust Load

Formula to calculate Overhung Load (OHL)

Transmission Elements Notes Factor fz
Spur or Helical Gears 17 teeth or more 1.00
less than 17 teeth 1.15
Chain & Sprockets 20 teeth or more 1.00
less than 20 teeth 1.30
less than 13 teeth 1.40
Timing Belt & Pulley 1.30
V-Belt & Pulley dependent on pre-tension 1.50~2.00
Flat Belt & Pulley with tension roller dependent on pre-tension 2.00~2.50
Flat Belt & Pulley without tension roller dependent on pre-tension 2.30~3.00