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This article describes a series of tests that can be performed by the average user, with little experience, and without sophisticated measuring instruments, to quickly determine the most important performance characteristics of linear motion systems.
For the most accurate measurements,
miniature and instrument ball bearing
dimensions should be measured with a
calibrated air gauge. A good second option is a calibrated optical comparator. On occasion, it may be necessary to use a calibrated, hand-held micrometer to double-check a measurement or for simple verification while working in the field.
Grease lubrication has clear advantages over oil lubrication: Grease does not leak easily; it has sealing properties; and it protects bearing surfaces from corrosion. Its disadvantages are grease-life limitations and a limited cooling ability. Moreover, in some applications there is a risk of grease starvation, which leads to reduced
lubricating films. However, if the right grease, sealing system and/or lubrication system are chosen, then grease lubrication offers clear benefits. This article summarizes aspects of grease lubrication mechanisms in rolling bearings.
When designing a spur-crown pair, is there a formula, guideline or design guide for adapting the spur teeth for the radial angle of the teeth in the crown?
Dovetails, gears and splines have been widely used in aero engines where fretting is an important failure mode due to loading variation and vibration during extended service. Failure caused by fretting fatigue becomes a prominent issue when service time continues beyond 4,000 hours. In some cases, microslip at the edge of a contact zone can reduce the life by as much as 40–60 percent.
Everything started in 1800 when Volta developed the first DC battery. Faraday used the DC battery to develop the first electric motor. It used brushes to transfer the battery voltage and current to the rotating disk rotor. This was in mid-1831. Thus was born the brush DC motor.
The purpose of DC motor protection is
to extend a motor's lifespan by protecting
it from conditions that can damage the motor's windings--both electrically
and mechanically.