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Rheology models express the way tribological conditions translate to shear stress of the lubricant and friction force on the interacting surfaces. Due to the complexity of the lubricant rheology, the friction coefficient is usually obtained experimentally either under the same operating conditions or by curve fitting in a properly chosen friction map. The current study aims at determining the rheological parameters of a lubricant based on friction measurements carried out on a commercial, readily available ball-on-disc machine.
Rolling element bearings are widely used in mechanical transmission to reduce friction between two rotating parts. With the further development of the electrical motor in mechanical industry, REBs operate more and more at high rotational speed. For these applications, REBs power losses can
be predominant in mechanical transmissions.
Cylindrical gear design can be divided into three steps. In the first step, rough gear pair dimensions such as center distance and face width are being estimated. Center distance and face width are directly linked to the available space (housing dimensions) and influence the overall size, weight and cost of the gears.
Power density is a key factor in gear design. Increasing the power density enables engineers to use smaller gears for their applications which lead to smaller and lighter gear boxes. The benefit for example for the automotive industry is less moving load in the vehicles and therefor a reduction of fuel consumption and subsequently a reduction of CO2 emission. The limiting factor for the increase in power density of gears is the material strength in regard to the critical failure mode.
When it comes to a steel-gear mesh, there are several common standards and design rules on how to reduce noise emissions in the mesh. But if plastic gears are involved, this is no longer the case. The topic of this presentation is to highlight
some of the differences between metal-and-plastic gear meshes, i.e. which design strategies can be stated as valid for metal as well as plastic and which are not?
Most of us want to just instinctively squeeze a belt between a pair of pulleys to test the belt tension. What is not as instinctive is just how much force such a procedure can put on the shaft -- often significantly past the manufacturer's rated limits for small motors. This can cause damage to both the shaft and the bearings.
Different motor types favor different application areas. No single style has advantages in all application spaces. Direct drive applications favor hybrid servos while high-speed, geared down applications tend to favor the conventional servo motors.
With the increasing mechanical power capacity of gearboxes, the thermal power limit tends to become the limiting factor. To achieve a balanced system, the gear unit needs extra cooling. Using a fan that is mounted to a fast rotating shaft is a common solution. For this solution an optimal design is investigated.
Over the many years, there have been many technical papers and articles about which motor is the best. The short and sweet answer is - let's talk about the application. More
recently a number of papers and articles have appeared that compared each motor's advantages and disadvantages in generic or specific terms. Many times, the methods used to drive and control these motors are not completely described due to the many control schemes available for use. A few articles focus on just the open loop step motor and the closed loop servo motor advantages and disadvantages in a laundry list format. This article is attempting to "drill down" into the reasons why and to describe how it is done.