If torque conversion with high gear ratio, compact installation space and 90-degree axis-crossing angle is needed, often worm gears are used. Due to their high power density and sliding speeds within the tooth contact, frictional heat and thermal stresses are higher compared to helical, bevel and hypoid gears, and thus the thermal load capacity of worm gears is lower.
In the selection of lubricating greases for plastic worm gears, the user needs to know the influence of each grease constituent on the tribological performance in order to choose the appropriate lubricant. In this work, the effect of NLGI class, viscosity, base oil and thickener type are investigated separately regarding the efficiency and temperature close to the tribocontact. With the help of this contribution the user understands the effect of each parameter and learns about the potentially reachable efficiency and temperature ranges.
A worm drive is a geared power transmission device in which a worm meshes with a worm gear to transmit power between two non-intersecting shafts that are oriented at a right angle. The worm drive has been an active and challenging topic of technological study since Leonardo da Vinci (1452-1519).
I have a fairly straightforward question about a worm gear segment. But as of yet, I haven’t gotten a straight answer from any of the gear job shops I’ve approached about this job. Is there a "traditional" gear cutting method that can produce a ~180
degree enveloping worm gear segment when a feature on the back of the part will interfere with a complete rotation of the part? Or am I left with only the option of 4- or 5-axis surfacing with a CNC mill? I have presented this part to several well-known gear shops in the U.S. without a straight answer on how the part can be made. Any help you could offer would be appreciated.
This paper presents a physically grounded calculation method to determine the
efficiency of worm gear drives. This computation is based on the Institute of Machine
Elements, Gears, and Transmissions (MEGT) tribological simulation, which can determine the local tooth friction coefficients (Ref. 1). With this knowledge other power losses such
as the bearings, oil churnings and seals power losses can also be calculated.
Varying installation requirements for worm gears, as, for example, when used in modular gear systems, can necessitate grease lubrication - especially when adequate sealing for oil lubrication would be too complex. Such worm gears are being increasingly used in outside applications such as solar power plants and slew drives. While knowledge about the operating conditions is often appropriate, the basic understanding for load capacity and efficiency under grease lubrication is quite poor. Investigations done at FZG and sponsored by FVA/AiF are shown here to give an impression of the basic factors of load capacity and efficiency. The results of the investigation indicate a satisfying quality of calculations on heat, load capacity and efficiency based on characteristic parameters of the base oil with only slight modifications to the methodology known from DIN 3996 or ISO TR 14521.
Beginning with a brief summary and update of the latest advances in the calculation methods for worm gears, the author then presents the detailed approach to worm gear geometry found in the revised ISO TR 10828. With that information, and by presenting examples, these new methods are explained, as are their possibilities for addressing the geometrical particularities of worm gears and their impact upon the behavior and load capacity of a gearset under working conditions based on ISO TR 14521 — Methods B and C. The author also highlights the new possibilities offered on that basis for the further evolution of load capacity calculation of a worm gearset based on load and contact pressure distribution.