Gearboxes and Gearheads - Insights

New rack and pinion systems requiring more from gearboxes. New semiconductor manufacturing requiring cleaner gearboxes with higher performance. New packaging equipment requiring higher throughput demand more from gearboxes (and robots that use gearboxes).

User and environmental friendliness. Compact design and minimum weight. Torque capacity and low noise performance. Easy to install.

Hybrid and electric vehicles are changing the way we think about power transmission. I don't think they will ever disappear, but certainly on the decline.

SEW-Eurodrive, Thompson, Siemens, Wittenstein Alpha GmbH, the list goes on...

Sumitomo by far. They have a very complete line of products to meet every application, plus the guarantee. The best model that I ever work with is the Cyclo.

Peerless-Winsmith, HiTek Services (Owens Cross Roads, Alabama), Sumitomo, and in the past, the United Shoe Machinery harmonic drive of the 1970s.

Bridle application, Flattener, Pinch roll, Irrigation application, Cement industries, Cooling tower gearbox, Right angle drive gearbox, hot roll mill application, uncoiler - recoiler gearbox, paper industries, extrusion application (Plastic + Rubber) etc...

Tidal power generator designs. 3D laser prosthetic and orthotic scanner assemblies. Down hole production pipe and casing damage scanners. Oil & Gas well and pipe emergency closure equipment and etc.

Crane luffing gearbox (quadruple threaded screw rod driven from helical spur wheel gearing, cardanic frame for supporting the gearbox housing, special lubrication system for spindle bronze nut)

Too many to mention - one strange one was a Greyhound treadmill and a carousel for exercising race horses.

Rotating a 300 ton furnace. Applications this size normally makes use of heavy industrial equipment. In this case, the customer made use of light to medium geared motors in combination with servo technology. A very unique design.

Direct mounting of index table onto worm-type or helical gear box without external guides or thrust bearings.

Yes. Mostly, the use of these systems in the field, with many, many wind induced load cycles over the years results in a fatigue failure. This is especially true, I think, with high gear reduction systems, because the backlash/compliance allow the wind induced vortex shedding loads to induce high movement of the structure (say, a heliostat or parabolic dish concentrator) and this puts very high impulse loads on the input stages. There are various failures under field conditions that are likely due to this.

Had a customer purchase a planetary gearbox and use it in a wind turbine. Installed it backwards to increase the output speed and the gearbox ripped itself apart because the misuse of the gearbox design. Also had a different customer who kept going through gearboxes in less than 2,000 hrs of use because he did not calculate over hung load in the sizing of the gearbox.

In a paper mill, a 80 HP electric motor and gear box broke down and the only replacement locally available was a 60 HP and gear box. When power was turned on, the machine ceased and was damaged. The plant was down for two weeks.

High efficiency, no back drive from imposed loads, ability to modulate impact load to reduce fatigue induced failures, permanent lubrication, ease of assembly/dis-assembly by relatively unskilled labor without special tools and equipment, ease of inspection and assembly under field conditions, high strength and stiffness....and of course, low cost.

No compromise in choice of material. No compromise in bearing quality. The gear box mounting platform has to be correctly pre-machined to make sure there is no additional stress or forces when mounting the GB.

Cycloidal disc with roller pin and rollers, with all rolling contact parts so that wear and tear is less than simple gears. Also in some range they have grease lubrication to avoid leakage.

Oversizing of the unit relative to the application. For example, if I calculate that a conveyor needs 2.1 kw of power at a given speed, I will generally add 25% and in this case would recommend 3kW. The client may then say that we should go for a 4kW. We then add a service factor of 1.5 based on the installed power of 4kW and the client ends up with a 4kW motor and a gearbox rated for 6kW - on an application that only requires 2.1kW. Also if the client can first establish the actual torque required - this can be a major help in sizing the unit correctly.

Speak to the suppliers. Confirm dimensions and data is suitable and confirm the data in writing. If in doubt, ask for clarification. Doing things in hard copy protects the customer and supplier simultaneously.

In German standard DIN 15017E, there are detailed instructions for how to calculate the peak torque acting on shafts, gear-wheels - if the max. value of acceleration-torque or braking-torque caused by motor, and due mechanical brake..... are known, as also the mass inertia of motor, shafts, coupling etc.

There are some new designs that hardly anyone knows about, because the main manufacturers don't consider them sufficiently mature, or they are concentrating on their own product line. Also, be absolutely sure that the ratings for the gear boxes are consistent in terms of stress. I've discovered that in some cases the big gearboxes have a higher "Name Plate Rating" for torque or force that actually results in a much higher stress on the components than the smaller gear boxes. So, the big ones have a much shorter life. In one case, the life was stated to be 100,000 inches of travel for the big ones, and 1,000,000 inches for the smaller ones, but there were no precise data...it was essentially anecdotal, but still instructive.

When selecting service factory use AGMA rating systems instead of DIN Standards. DIN tends to be too light. Check for shock loading in applications. Don't always buy on price, understand your application and service factor requirements.

Make sure when comparing geared motors that you keep in mind that you need to compare similarly rated gearboxes. For example, you need to compare worm geared motors with worm geared motors and helical geared motors with helical geared motors. You need to keep an eye on the service factors and also whether the gearbox comes filled with oil. A major consideration should be whether the motor used is a standard motor or a designated motor. I personally would always recommend that clients would use standard AC designed motors as when it comes to replacement costs they are a fraction of the price of a designated motor.