Twenty-eight female guards were unfairly dismissed by a security company because the client‚ Metrora.
Cast your mind back 100 years to the cobbled streets and rutted roads of Europe and America, on which spindly motor cars mingled with horse wagons, buggies and riders.
I f the car's engine stalled , it was quite an operation to start it again. First, you retarded the ignition with the lever on the steering wheel, then you got out, retrieved the crank handle from under the seat, and crouched in front of the car while you inserted the handle into a slot somewhere in the bumper or bodywork so that it engaged with the crankshaft.
You turned the crank handle slowly until it came up against compression and then, with a rapid, upward swing of arm and shoulder, you spun the engine, remembering never to put your thumb around the handle.
If you were lucky, the engine started with the first swing. But more often it took several swings and considerable verbal encouragement.
If you hadn't retarded the ignition enough, the engine backfired and the handle kicked back viciously.
If that happened, and you hadn't pulled away, you risked a broken arm or, worse, a dislocated thumb.
It was such incidents that led to the development of the electric starter.
In December 1910, one Byron Carter, a motoring pioneer, stopped to help a woman whose car had stalled on a bridge in Detroit. As he hand-cranked her engine, it backfired, spinning the handle backward. Poor Mr Carter wasn't nimble enough: he ended up in hospital with a broken arm and a shattered jaw. He developed complications and died.
Henry Leland, then head of General Motors' Cadillac division, knew Carter and was shocked by his death. He assembled a team of Cadillac engineers to find a better way of starting an engine than using the infamous crank handle.
Charles Kettering, who played such an important role in the development of the distributor-and-coil ignition system, was roped into this project and, thanks largely to his genius, Cadillac's famous 1912 model appeared with an electric starter motor.
The starter motor was fully integrated into the electrical system, which included a battery recharged by a generator that was driven by the engine, and electric headlights to replace the acetylene lamps previously used.
By 1920, nearly every car had a "self-starter." And, in due course, the starting handle disappeared from the tool-kits of new cars, not without misgivings in the ranks of older motorists who felt that, as long as you had a starting handle, you would never be stranded with a flat battery.
A starting handle was also a useful accessory when adjusting valve clearances, because it made it easy to rotate the crankshaft by precise amounts.
A starter motor is a direct current electric motor, which converts electrical energy stored in the battery into the mechanical energy of a rotating shaft.
Like a generator, a starter motor uses field coils to create a magnetic field around an "armature," a series of wire loops around a shaft. At one end of the shaft you find the commutator segments through which current can be fed into the armature windings by means of four carbon rods.
At the other end of the shaft is a small gear, called the pinion, which can be moved forward and backward along the shaft.
It meshes with the ring gear on the flywheel at the right moment and transmits the rotations of the spinning armature to the flywheel and to the crankshaft.
When the starter motor is operating, current from the battery flows through the field coils, creating a strong magnetic field around the armature.
At the same time, current is sent through the armature windings via the carbon brushes.
A current-carrying conductor in a magnetic field will experience a lateral force, and it's this force that makes the armature spin and crank the engine.