Spiral bevel gearboxes are often selected for continuous running applications due to their high efficiency ratings up to 96%. However, in low ratio configurations, the input and output shafts will be running at higher speeds resulting in greater heat generation. A properly sized gearbox will be able to dissipate the heat effectively and the temperature will stabilize to an acceptable level.
While there are several factors that impact the gearbox temperature, two important considerations are the input running speed and mounting orientation. These two criteria will help to determine if minor adjustments can be made to the gearbox during assembly to aid heat dissipation. Adjustments can be made to the backlash, bearing pre-loads, lubrication (volume/viscosity), and a vent filter or oil cooling system may ultimately be required. Spiral bevel gearboxes that cannot be adjusted may not be suitable for continuous running applications.
The chart above graphs the housing temperature of a V-Series gearbox (blue-dash) and a competitive spiral bevel gearbox (red-dotted) of comparable size. Both gearboxes were 1:1 ratios and tested at a continuous input speed of 1,800 RPM for 2 hours. Because the V-Series gearbox (blue-dash) was sized and assembled for the continuous application, it was able to dissipate the heat properly allowing the temperature to stabilize to an acceptable value of approximately 80°C. The competitive spiral bevel gearbox (red-dotted) could not dissipate the heat and the gearbox temperature continued to rise to 140°C before the test was terminated to avoid eventual failure.
To help prevent a spiral bevel gearbox from failing due to overheating, it is important to specify the duty cycle, input running speed, and mounting orientation. Those criteria are specified in GAM's V-Series type code to help ensure the gearbox is ordered and assembled to best suit each application.