Posted tagged ‘spiral’

TYPES OF GEARS

September 13, 2011

A SPUR GEAR

is cylindrical in shape, with teeth on the outer
circumference that are straight and parallel to the axis (hole).
There are a number of variations of the basic spur gear,
including pinion wire, stem pinions, rack and internal gears.
(See Figure 1.17)

PINION WIRE
is a long wire or rod that has been drawn
through a die so that gear teeth are cut into its surface.
It can be made into small gears with different face widths,
hubs, and bores. Pinion wire is stocked in 4 ft. lengths.
(See Figure 1.18)

STEM PINIONS
are bore-less spur gears with small numbers of
teeth cut on the end of a ground piece of shaft. They are
especially suited as pinions when large reductions are
desired. (See Figure 1.19)

RACK
are yet another type of spur gear. Unlike the basic spur
gear, racks have their teeth cut into the surface of a straight
bar instead of on the surface of a cylindrical blank. Rack is
sold in two, four and six foot lengths, depending on pitch,
which you will learn about starting in chapter 2.
(See Figure 1.20)

INTERNAL GEARS
have their teeth cut parallel to their shafts
like spur gears, but they are cut on the inside of the gear blank.
(See Figure 1.21)

HELICAL GEARS
A helical gear is similar to a spur gear except that the teeth
of a helical gear are cut at an angle (known as the helix
angle) to the axis (or hole). Helical gears are made in both
right and left hand configurations. Opposite hand helical
gears run on parallel shafts. Gears of the same hand operate
with shafts at 90-degrees. (See Figure 1.22, 1.23, 1.24, 1.25)

BEVEL GEARS
A bevel gear is shaped like a section of a cone and usually operates
on shafts at 90-degrees. The teeth of a bevel gear may be straight
or spiral. If they are spiral, the pinion and gear must be of opposite
hand in order for them to run together. Bevel gears, in contrast
to miter gears (see below), provide a ratio (reduce speed) so the
pinion always has fewer teeth. (See Figure 1.26, 1.27)

MITER GEARS
Miter gears are identical to bevel gears except that in a miter
gear set, both gears always have the same number of teeth.
Their ratio, therefore, is always 1 to 1. As a result, miter gears
are not used when an application calls for a change of speed.
(See Figure 1.28, 1.29)

WORMS & WORM GEARS
WORM Worms are a type of gear with one or more cylindrical
threads or “starts” (that resemble screw threads) and a face that
is usually wider than its diameter. A worm gear has a center
hole (bore) for mounting the worm on a shaft. (See Figure 1.30A)

WORM GEARS – like worms – also are usually cylindrical and
have a center hole for mounting on a shaft. The diameter of
a worm gear, however, is usually much greater than the
width of its face. Worm gears differ from spur gears in that
their teeth are somewhat different in shape, and they are
always formed on an angle to the axis to enable them to
mate with worms. (See Figure 1.30B)

Worms and worm gears work in sets, rotating on shafts at right
angles to each other, in order to transmit motion and power
at various speeds and speed ratios. In worm and worm gear sets,
both the worm and worm gear are of the same hand. (Because
right- hand gearing is considered standard, right-hand sets will
always be furnished unless otherwise specified.) (See Figure 1.30)

 

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PULLEY

August 23, 2011

Pulley:

01-standard pulley-spun end curve crown pulley-steel pulley-straight faced pulley-pulley mechanism-pulley ratio-pulley size-pulley selection

The diameters of standard pulleys are: 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1400 and 1600 mm. pulley may be straight faced or crowned. The crown serves to keep the belt centered. The height of the crown is usually 0.5% of the pulley width, but not less than 4 mm. The pulley diameter Dp depends on the number of plies of belt and may be also be determined from the formula:

Dp > K.i (mm)

Where

K = a factor depending on the number of plies (125 to 150)

i = no of plies

The compound value should be rounded off to the nearest standard size. While selecting the pulley diameter it should be ascertained that the diameter selected is larger than the minimum diameter of pulley for the particular belt selected.

The drive pulley may be lagged by rubber coating whenever necessary, to increase the coefficient of friction. The lagging thickness shall vary between 6 to 12 mm. The hardness of rubber lagging of the pulley shall be less than that of the cover rubber of the running belt.

Pulley types:


Pulleys are manufactured in a wide range of sizes, consisting of a continuous rim and two end discs fitted with hubs. In most of the conveyor pulleys intermediate stiffening discs are welded inside the rim. Other pulleys are self cleaning wing types which are used as the tail, take-up, or snub pulley where material tends to build up on the pulley face. Magnetic types of pulleys are used to remove tramp iron from the material being conveyed.

Typical welded steel pulley-Drum conveyor pulley

01-typical welded steel pulley-pulley types-pulley design-pulley system-pulley problems-pulley size

Spun end curve crown pulley

01-conveyor pulleys-spun end crown pulley-self cleaning wing pulley-snub pulley-pulley face-magenetic pulley

Spiral drum conveyor pulley

01-spiral drum conveyor pulley-pulley types-pulley with ball bearings-pulley for handling bulk load

Welded steel pulley with diamond grooved lagging

01-types of pulley-welded steel pulley-grooved lagging-belt conveyor drive-belt conveyor resistance-belt wrapping over pulleys

Welded steel pulley with grooved Lagging

01-welded steel pulley with grooved lagging-pulley types-belt conveyor speed reduction mechanism-belt conveyor drive arrangement

Spiral Wing Conveyor pulley

01-spiral wing conveyor pulley-belt conveyor calculation-belt conveyor formula-belt conveyor gallery

 

Power calculation for the drive unit:

The horse power required at the drive of a belt conveyor is derived from the following formula:

H.P = Te . V

Where

Te is the effective tension in the belt in N

V = velocity of the belt in m/s

The required effective tension Te on the driving pulley of a belt conveyor is obtained by adding up all the resistances.