SPIRAL BEVEL AND HYPOID EQUIPMENT

IN SPIRAL BEVEL and HYPOID gear generating machines the same rolling out principle is applied as in straight bevel machines, but a circular face mill cutter is used instead of the reciprocating tools, and a tooth space is cut instead of the two sides of a tooth. This is seen in illustration No. 10. It produces gears with lengthwise tooth curvature which have zero spiral angle in Zerol bevel gears or a spiral angle ranging up to 40° or 45° in spiral bevels and up to 55° in the pinion of a pair of hypoid gears. The machine shown in illustration No. 11 is the No. 16 Hypoid Generator. Several sizes of machines of this type are available, and gears up to 33" diameter can be cut.

Illustration No. 11

No. 11 Hypoid Generator (35940 bytes)

Cutters vary in diameter from 1.1" up to 18" (See illustration No. 12).

Illustration No. 12

Hypoid gear cutter (33661 bytes)

Roughing machines are available in the sizes where mass production prevails. Grinding of spiral bevel and hypoid gears is accomplished in principle when a grinding wheel is substituted for the circular face mill cutter and suitable dressing mechanism is provided for the wheel, as in the No. 7 Hypoid Grinder (Illustration No. 13).

Illustration No. 13

No. 7 Hypoid Grinder (31003 bytes)

Machines of this type are very highly organized, with a completely automatic cycle controlling the number of grinds, amount of stock removal for each grind, number and position of dressing operations in the cycle, and amount of wheel reduction per dress. This control of the cycle assures very uniform results, free from burning, and is an outstanding improvement in the art of grinding gears. The wheel dressing mechanism shown in illustration No. 14 uses a single diamond for both sides and point of the wheel.

Illustration No. 14

Wheel dressing mechanism(51275 bytes)

An excellent example of the use of hypoid gears is seen in the trucks of the modern electric street cars such as are in use here in Washington, and a score of other cities.

Illustration No. 15

ill15.jpg (49457 bytes)

This is shown in the photographic view (Illustration No. 15), and diagramatically in the line drawing (Illustration No. 16).

Illustration No. 16

Diagram of trolley car truck (16686 bytes)

There are two pairs of these hypoids in each truck, the gear member having ground teeth. The hypoid gears are an important factor in the quiet and smooth operation attained in these cars.