This model was first placed on the market in May, 1924; production ceased when the Corona plant was retooled for War efforts in 1941. The chief difference between it and earlier models are that it has a standard 4-bank, single shift keyboard, and it does not fold. It is low in design, being 4-1/2 inches high overall.
It has 42 full size keys with standard distance between each, making this model suitable interchangeably with standard office typewriters. It has a 10-inch carriage, permitting insertion of No. 10 envelopes, and writes a line 8.3 inches long (83 pica spaces) ; Ball bearing, carriage shift with right and left hand shift keys, left hand line space and carriage return lever, standard 12-yard, 2-color ribbon with automatic and manual reverse ; variable line spacer and carriage release lever at both ends of carriage. The margin release and back-spacer keys are located in the keyboard.
This model has an accelerating type bar action, which means that the type bars are so constructed that they reach their highest speed at the printing point, thus obtaining maximum power of impact of type face against the writing surface, providing clean-cut type impressions, efficient stencil-cutting ability and manifolding power.
It has double universal bars: one bar, operated by the key levers actuates the ribbon movement, and the other, operated by the type bars, actuates the escapement. This construction permits of independent adjustment of ribbon and escape mechanisms and affects a light even touch.
Specifications of Model Four
General Features: Portable size, front stroke, carriage shift, straight line visibility. This model does not fold.
Keyboard: Four rows; provision made for dead keys if requested; right and left hand shift keys with left hand shift lock and release; back-space key located in the keyboard, equipped with positive stop to prevent carriage moving more than one space at a time.
Carriage: Mounted on ball and roller bearings; takes paper 9-7/8 inches wide; Writing line 8.3 inches long. Left hand line space and carriage return lever with adjustment for single and double line spacing. Right and left hand adjustable margin stops mounted on a slide, marked with scale to correspond with markings on the paper scale; line lock release located in keyboard.
Printing Mechanism: Type bars are flat steel with heels to prevent battering; mounted in solid slotted segment; carriage shift; mechanical type guide at printing point. 2-color, 1/2-inch ribbon, 12 yards long, with automatic and manual reverse, and cut out for stencil work.
Construction: Stamped aluminum frame, one piece, reinforced with three rigid cross members, one of which is integral with the frame. Size of machine, 11 x 12-1/2 x 4-1/4 inches; outside dimensions of case, 13-1/2 x 12-1/2 x 4-7/8; inches. Weight: 12 pounds with case; 9-1/4 pounds without case. Finish: Black enamel until CORONA began using DuPont DUCO® finishes, later models have crystaline panals that may be colored rose gold or another DUCO® finish, with nickel trim. Type faces: Pica, elite, medium Roman, billing or italic.