RUSH GEARS inc.™ BEVEL and MITER GEARS are used as right angle
drives where high efficiency is required. They transmit motion and
power between right angle (90°) intersecting shafts at speed ratios from
1:1 (Miters) and 1.5:1 to 6:1 (Bevels).
Bevel and Miter Gears are usually cut 20° pressure angle with the long
and short addendum system being used to compensate for tooth
undercut in gears and pinions having low numbers of teeth.
Only Miter Gears of the same number of teeth, pitch and pressure angle,
will operate together. However, more than two like miters may be used
in a set such as a differential arrangement.
Bevel Gears and Pinions are listed in pairs and are not interchangeable
with gears of a different pitch, pressure angle or ratio. It is advisable
when replacing a worn gear to replace the complete set, particularly in
low ratio sets.
CONIFLEX TOOTH FORM: In addition to using the long and short
addendum system, most all RUSH GEARS inc.™ miter gears and bevel
gear sizes are generated cut with the Coniflex tooth form. This form has
a localized tooth bearing running lengthwise along the gear tooth and
because of the localization of tooth contact permits some realignment
of gears at assembly and during operation without heavy loading at the
toe or heel of the tooth.
MOUNTING: When mounting bevel and miter gears it is important that
shafts be exactly 90° apart to eliminate mis-alignment of bevel or miter.
The Coniflex tooth form will permit a slight adjustment in assembly, but
should not be used to overcome severely mis-aligned shafts. Gears
should be mounted at the correct distance from the cone or apex center
with thrust bearings used in back of the hubs to absorb the backward
thrust created in this type of gearing.
The MOUNTING DISTANCE ("MD") dimension shown for each Miter or
Bevel Gear is the distance from the back end of the gear hub of one gear
to the centerline of its mating gear. When properly mounted to this
dimension, the ends of the teeth of these gears will be flush with each
other. If the mounting distance is too long the gears will not be fully in
mesh, thus permitting the load to be concentrated above the pitch line
and allowing excessive backlash. When distance is too short, gears
may bind causing excessive heat, wear and breakage.
LUBRICATION: Adequate lubrication is a necessary factor in this type
of gearing to insure longer life of gears and bearings. Residual type
(straight mineral) oils are recommended for exposed gearing, hand or
bath lubricated. Intermediate Viscosity oils for enclosed gearing subject
to moderate temperatures should prove satisfactory in normal operation.
Heavy duty application, where pressures or shock loads are moderate to
high require Mild Extreme Pressure (EP) lubricants. Specific
recommendations can be made by engineers of the many oilcompanies
in this field.