The continuous rated capacity series worm gear are often limited by the ability of housing to dissipate heat without developing gear friction and excessive temperatures ways. Typically, the oil temperature must exceed about 200ºF (93 ° C) for satisfactory operation. The basic relationship between temperature rise and heat dissipation rate used for journal bearings hold good for worm gearbox.
Where H – Time rate of heat dissipation (Nm/sec)
CH – Heat transfer coefficient (Nm/sec/m2/ºC)
A – Housing external surface area (m2)
To – Oil temperature (ºC)
Ta – Ambiant air temperature (ºC)
A possible surface area of traditional housing designs considered roughly from 15.27.
Where in m2 and C (the distance between the shafts) in m. Can make housing surface area much greater than the value of the above equation incorporate cooling fins. Can rough estimate of C building of the following Fig.15.12.
The guidelines are designed to select the lead angle, pressure angle, dedendum appendix, helix angle and the minimum number of teeth on the worm gear given in Tables 15.5 to 15.8.