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The torsional deflection of a simple cylinder cannot radiate efficiently acoustic noise, but with particular boundary conditions the stator can radiate acoustic noise under torque ripple excitation. [8] Structure-borne noise can also be generated by torque ripple when rotor shaft line vibrations propagate to the frame [9] and shaft line.
The light may dim briefly as the motor starts. When the armature is not turning (called locked rotor) there is no back-EMF and the motor's current draw is quite high. If the motor's starting current is high enough, it will pull the line voltage down enough to cause noticeable dimming of the light.
Back-up beepers or an observer are required by OSHA for earth-moving vehicles with an obstructed view to the rear and no one on the ground to help guide the driver. [9] OSHA regulation 29 CFR Part 1926.601(b)(4) requires "a reverse signal alarm audible above surrounding noise level", but only when the motor vehicle has "an obstructed view to the rear".
The American auto industry voluntarily adopted amber front turn signals for most vehicles beginning in the 1963 model year, [67] [68] though the advent of amber signals was accompanied by legal stumbles in some states [69] [70] and front turn signals were still legally permitted to emit white light until FMVSS 108 took effect for the 1968 model ...
These will absorb a part of the vibrations (and the noise) produced by the machines. To control the electromagnetic vibrations at the origin, skewing the electric motor or choosing a better slot/pole combination [3] will reduce electromagnetic force harmonics or avoid resonances between magnetic forces and structural modes of the electric motor.
Counter-rotating propellers generally turn clockwise on the left engine and counterclockwise on the right. The advantage of such designs is that counter-rotating propellers balance the effects of torque and P-factor, meaning that such aircraft do not have a critical engine in the case of engine failure.
Contra-rotating propellers Contra-rotating propellers on the Rolls-Royce Griffon-powered P-51XR Mustang Precious Metal at the 2014 Reno Air Races. Aircraft equipped with contra-rotating propellers (CRP) [1] coaxial contra-rotating propellers, or high-speed propellers, apply the maximum power of usually a single piston engine or turboprop engine to drive a pair of coaxial propellers in contra ...
Engine balance refers to how the inertial forces produced by moving parts in an internal combustion engine or steam engine are neutralised with counterweights and balance shafts, to prevent unpleasant and potentially damaging vibration. The strongest inertial forces occur at crankshaft speed (first-order forces) and balance is mandatory, while ...