TRANSMISSION SYSTEM: GEAR DRIVE
GEARBOX
FUNDAMENTAL, OPERATION
&
MAINTENANCE
Presentation by
Nirjhar Chakravorti
Features…
► Introduction
► Why
gears are used?
► Fundamentals of gearing
► Classification of gears
► Gear Making process
► Type of gear boxes
► Material for gear boxes
► Gear lubrication and cooling
► Gear failures
► Trouble shooting
► Market products and specification
Introduction
The term gear is defined as a machine
element used to transmit motion and
power between rotating shafts and by
means of progressive engagement of
projections called teeth.
Toothed gearing system evolved gradually
from the primitive forms where wooden pins
were arranged on the periphery of simple
wooden wheels to drive opposite member of
the pair. These wheels served the purpose of
gears those days. Of course the operation was
neither smooth nor quite and obviously speeds
were very slow. The motive power to turn
these systems was generally provided by the
trade mills, which were operated by men,
animals and windmills.
Archimedes knew primitive forms of
gear before the Christian era. Leonardo
de Vinci used the concept of gear
system in many of his proposed
machines.
In recent times, however, the
technologists and engineers have
concentrated their efforts to device
curves for gear teeth, which would
provide constant relative velocity of the
gear tooth faces. With the invention of
various geometric curves (such as
involutes, cycloids) the gearing system
has become very attractive, quite and
continuous.
For the evolution of modern day gearing
technology we must acknowledge the
contribution of scientists like Louise,
Buckingham, Euler.
Why gears are used?
►
To transmit torque/ power from one shaft to
another shaft.
Other commonly used power transmitting elements:
 Belt drive
major limitation: Slippage
 Rope drive
 Chain drive
major limitation: Discontinuous drive
To avoid slippage and discontinuity during power transmission, the best
solution is gear drive.
►
►
►
To get desired rotational speed
To change direction of rotation
Where distance between drive shaft and driven
shaft is very small
Disadvantages of gear drive
Disadvantages:
• Gear drive is costlier than other drives
• Error during cutting teeth causes
vibration & noise while operation
• Gear drive requires proper lubrication
for smooth running
So as usual, designers has to be logical
and optimal during selection of drive.
Fundamental of Gearing
How gears transmit power and motion: Concept of friction
wheel
The motion and power transmitted by gear is kinematically
equivalent to that transmitted by friction wheel.
Consider two circular wheels A & B mounted on two parallel
shafts and the wheels are pressed against each other. Shafts
are mounted on anti-friction bearings.
When wheel A is rotated by shaft, it will rotate wheel B in
Force on the system:
opposite direction. • R = Normal reaction between two rubbing wheels
N
F=µRN
RN
A
T
B
(Separation force)
• T= Tangential force
Frictional Force (F= µRN),
• F=
where µ= co-efficient of friction
When T≤ µRN wheel B will rotated by wheel A
When T> µRN slippage will take place
How to prevent this slippage?
► Simply by increasing the frictional resistance
between the two surfaces. To increase this
frictional resistance, a number of projections
(called teeth) are made on the periphery of
both the wheels.
► A friction wheel with teeth cut on it is called
gear.
Gear Tooth Terminology
Important definitions
Pitch circle:
It is the imaginary circle that rolls without
slip with a pitch circle of a mating gear.
► Pitch Point:
It is the point of tangency of two pitch
circles and is on the line-of-centers. The
pitch point of a tooth profile is at its
intersection with the pitch circle.
►
►
Circular pitch:
It is the distance measured on the
circumference of the pitch circle from a
point on the tooth to the corresponding
point on the next tooth. Mathematically,
circular pitch, pc=∏D/T,
where,
D= P.C.D.
T= No. of teeth
►
Module:
It is the ratio of the pitch circle diameter in
millimeters to the number of teeth.
Mathematically, Module, m=D/T
The recommended series of the modules in
Indian standard are
1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16,
20, 25, 32, 40, 50.
►
Backlash:
It is the distance between the tooth space and the tooth
thickness of mating gear as measured on the pitch circle.
Purpose of backlash:
 prevent gears from jamming together
 making contact on both sides of their teeth
simultaneously.
 Lack of backlash may cause noise, overloading,
overheating of the gears and bearings, and even seizing and
failure.
Excessive backlash is objectionable, particularly if the drive is
frequently reversing, or if there is an overrunning load as in
cam drives. Excess backlash causes noisy operation.
Backlash does not affect involute action.
►
Pressure Angle:
If a tangent is drawn to the involute profile
of a tooth at any point on the curve, and if a
radius line is drawn through this point of
tangency connecting this point with the
centre of the gear, then the acute angle
included between this tangent and radial
line is defined as pressure angle at that
point.
In gear design, the pressure angle is
measured at the pitch point.
Principle of transmission &conjugate
action
When a pair of gear teeth act together
against each other, rotary motion is
produced which is transmitted from the
driver to the driven gear. If such a pair of
tooth profiles which are so designed that a
constant angular velocity ratio is produced
and maintained during meshing, the two
gears are said to have conjugate action and
the tooth profiles are said to have conjugate
curves.
Conjugate action
In other words, conjugate action is assumed
if, ω1/ ω2=constant, where,
ω1= Angular velocity of the driver (generally called pinion)
ω2= Angular velocity of the driven (generally called gear)
In case of conjugate action,
ω1/ ω2= D2/D1
D1= PCD of pinion
D2= PCD of gear
Gear teeth profile
To produce conjugate action, following
tooth profiles are used:
► Involute teeth
► Cycloidal teeth
► Epi-cycloidal teeth
► Hypo cycloidal teeth
Involute curve
The involute curve is most easily understood
as the trace of a point at the end of a taut
string that unwinds from a cylinder. It is
imagined that a point on a string, which is
pulled taut in a fixed direction, projects its
trace onto a plane that rotates with the
base circle. The base cylinder, or base circle
as referred to in gear literature, fully defines
the form of the involute and in a gear it is
an inherent parameter, though invisible.
Involute curve
► Involute
teeth is most commonly used
profile for industrial gears.
Cycloidal curve
► Consider
a point, “P” on the perphery of a
circle. Now if the circle rolls on a fixed line,
then the contour made by the point “P”, is
known as cycloidal curve.
► If the circle rolls on the outer periphery of
another circle (which is fixed), then the contour
made by the point “P”, is known as epi-cycloidal
curve.
► If the circle rolls on the inner periphery of
another circle (which is fixed), then the contour
made by the point “P”, is known as hypocycloidal curve.
Cycloidal curve
P (Trajectory followed by point “P” is
called Cycloidal Curve)
P (Trajectory followed by point “P” is
called Epi-cycloidal Curve)
Fixed circle
P (Trajectory followed by point “P” is
called Hypo-cycloidal Curve)
Fixed circle
Why involute curve is widely used?
The involute curve is almost exclusively used in
modern gearing system. The advantage of involute
profile over the cycloidal profile is given below:
► The
form of the basic rack tooth is
straight-sided, and therefore is relatively
simple and can be accurately made; as a
generating toolift imparts high accuracy
to the cut gear tooth. A hob cutter for
the cycloidal gear is not as easily made.
Continued to next page…….
Why involute curve is widely used?
►
In cycloidal gears, for a mating pair, there is only one
theoretical correct centre distance for which this will
transmit motion maintaining a constant angular velocity
ratio.
in case of involute gearing system, the centre distance
can be changed without affecting the angular velocity
ratio.
This advantage of involute system is of prime
importance as most of the modern gears are corrected
ones having changed centre.
Also, in case of gearing systems having standard centre
distance, it is not possible to accurately maintain that
distance due to mounting inaccuracies, misalignments
and a number of other diverse factors.
Continued to next page…….
Why involute curve is widely used?
► While
the cycloidal tooth profile has double
curvature, an involute tooth has single
curvature, which facilitates ease of
manufacturing.
► In involute profile as the path of contact is
straight line and the pressure angle is
constant, there is constant force acting on the
axes. In cycloidal gear, the pressure angle
continuously changes. This results in
separating forces of variable magnitude,
which in turn gives rise to unquiet operation.
Disadvantages of involute curve over
cycloidal curve:
► In
case of cycloidal gear, minimum number
of teeth can be as low as 6 or 7; but in case
of involute gears, minimum number of teeth
is 17.
► The cycloidal teeth is stronger than the
involute teeth. There is more material at the
root portion of the cycloidal tooth as
compared to an involute tooth.
► Involute teeth has the problem of
interference, but the cycloidal gears do not
have interference and the problem thereof.
Interference & Undercutting
► The
maximum length of the line-of-contact is
limited to the length of the common tangent.
► Any tooth addendum that extends beyond the
tangent points (T and T') is not only useless, but
interferes with the root fillet area of the mating
tooth. This results in the typical undercut tooth.
The undercut not only weakens the tooth with a
wasp-like waist, but also removes some of the
useful involute adjacent to the base circle.
► From the geometry of the limiting length-ofcontact (T-T') it is evident that interference is first
encountered by the addenda of the gear teeth
digging into the mating-pinion tooth flanks.
Continued to next page…….
Interference & Undercutting
Continued to next page…….
Interference & Undercutting
Geometry of proper teeth meshing
Tooth correction: One of the
method of avoiding undercut, is tooth
correction or tooth enlargement. This
is achieved by pinion enlargement (or
correction as often termed), wherein
the pinion teeth, still generated with a
standard cutter, are shifted radially
ourward to form a full involute tooth
free of undercut The tooth is enlarged
both radially and circumferentially.
Interference & Undercutting
► Interference
condition becomes more severe as the
number of teeth on the gear increases. The limit is
reached when the gear becomes a rack. This is a
realistic case since the hob is a rack-type cutter. The
result is that standard gears with tooth numbers
below a critical value are automatically undercut in
the generating process. The limiting number of teeth
in a gear
► meshing with a rack is given by the expression:
► Nc = 2/sin²α
► This indicates the minimum number of teeth free of
undercutting decreases with increasing Pressure
angle.
► For 14½º the value of Nc is 32, and for 20° it is 17.
System of gear teeth
Following four system of gear teeth is
commonly used:
► 14 ½ ° composite
► 14 ½ ° full depth involute
► 20 ° full depth involute
► 20 ° full stub involute
Classification of gears
According to the position of shafts:
►
Parallel shaft:
(i) Spur gear: gear teeth are straight along the length and
are parallel to the axes.
(ii) Helical gear:
(a) Single helical gear: the teeth are helices and these helices
may be left handed or right handed.
(b) Double helical gear (herringbone gear): these gears are
actually two helical gears of hands, placed side by side and
cut on the same blank to obtain composite unit.
►
►
Intersecting shaft:
(i) Bevel gear:
(a) Straight bevel gear: the gear blank is cone on which teeth
are generated. The teeth are straight.
(b) Spiral bevel gear: the elements are curved in the shape of
spiral, so that contact between intermeshing teeth become
gradual and continuous.
Non-intersecting and non-parallel shaft:
(i) Hypoid gear: these are similar to spiral bevel gears, but
have non-intersecting axes, ie. the axis of the pinion is offset
relative to the gear axis.
(ii) Crossed helical gear: these are cylindrical helical gears, but
their axes are at am angle when in mesh and do not intersect.
(iii) Worm gear: the axes are normally at right angles to each
other. The tooth elements of both the components are helices.
Classification of gears
Spur Gear
Straight Bevel Gear
Single Helical Gear
Spiral Bevel Gear
Double Helical Gear
Worm Gear
Gear Making process
Modern methods of producing gear teeth cover a
wide variety:
► Machining
► Grinding
► Casting
► Molding
► Forming (drawing, extruding, rolling)
► Stamping
Each method offers special characteristics relating
to quality, production quantity, cost, material and
application.
Machining
Machining constitutes the most important
method of generating gear teeth. It is
suitable for high precision gears in both
small and large quantities.
Various methods of machining is described
below:
► Teeth formation process
► Tooth finishing process
Teeth formation process
Gear Milling:
Basic Principle: After each tooth is milled,
gear blank is rotated to the next cutting.
► Disadvantage:
(1)Time consuming
(2) Involves heavy stock removal operation
which require high accuracy of indexing
mechanism
Hob generation:
This is the most widely used method of cutting gear
teeth.
► Basic Principle: In this process the work piece rotates in
constant relationship with the cutting tool ie. The gear
hob. The rack is in the form of a worm.
► The central section of the hob is identical to that of the
worm and gear. The differences are that the thread of
the hob is axially gashed or fluted in several places so as
to form cutting edges, while the sides and top of these
teeth are relieved behind the gash surface to permit
proper cutting action. This arrangement, in eftect, gives
an infinitely long rack so that cutting is both steady and
continuous. To generate the full Width of the gear, the
hob slowly traverses the face of the gear as it rotates.
Thus, the hob has a basic rotary motion and a
unidirectional traverse at right angles.
►
Hob generation continued to next page…….
Hob generation:
► Both
movements are relatively simple to effect,
resulting in a very accurate process.
► A further advantage of hobbing is that the hob can
be swiveled relative to the blank axis. This permits
cutting helical gears of all angles with the same
tooling.
► With regard to accuracy, hobbing is superior to the
other cutting processes. Gears can be directly
hobbed to ultra-precision
► tolerances without resorting to any secondary
refining processes.
Gear shaping:
► It’s a continuous generating process.
► Cutter is a gear with cutting edges. Profile is
generated with number of enveloping cuts
produced by the cutter teeth.
► It is time consuming as time is lost during
return stroke of cutter and half of the total
machining time is spent in metal removal.
Gear grinding:
Although grinding is often associated with quantity
fabrication of high quality gears as a secondary refining
operation, it is also a basic process for producing
hardened gears. In addition, many high-precision finepitch gears have their teeth entirely ground from the
blank state.
► There are a number of distinct advantages to ground
gears. These are listed as follows:
1. Achievement of high precision is possible because
the process can remove very little material in the final
pass.
2. Grinding results in a much finer surface finish than
any machining process.
3. Hardened steel alloys can be ground.
4. Residual surface stresses are minimal.
►
Grinding continued to next page…….
Gear grinding:
Ground gears’ superior load carrying capacity is not only due to
the hardened alloys higher mechanical properties, but also
because of the finer surface finish. A fine finish enables
maintenance of a good continuous oil film versus boundary
lubrication and breakthrough. The result is higher load capactry
along with reduced wear and longer useful life.
► Although there are distinct advantages for ground gears, there
are some limitations and disadvantages. These are:
1. Grinding is limited to ferrous materials.
2. Hard metals grind better than soft ones.
3. Grinding of helicals and worms has limitations that possibly
involve profile deviations and removal.
4. Pro-grind hobbing requires special protruberance hobs to
provide grind wheel clearance at the root.
5. Gear grinding machinery is scarcer than hobbing machines.
6. Grinding is a secondary operation which increases total gear
cost
► Despite involving higher cost and other limitations, ground gears
are always superior in precision and strength.
►
Tooth finishing process
Lapping:
► Gear finishing process, used after heat treatment.
► It improves surface finish, correct distortions and
improved wear life.
► Lapping also contribute to have proper backlash,
between meshing teeth.
Other tooth finishing operations are shaving,
honning, etc.
Type of gearbox
Generally following gearboxes are used in
industries:
► Helical gearbox
► Bevel-helical gearbox
► Worm gearbox
► Heli-worm gearbox
► Geared motor
Material
Gear steels may be divided into two general
classes:
► the plain carbon
► the alloy steels.
Alloy steels are used in the industrial field,
but heat-treated plain carbon steels are also
common.
The advantages obtained from using heat-treated alloy
steels in place of heat-treated plain carbon steels are
as follows:
1) Increased surface hardness and depth of hardness
penetration for the same carbon content and quench.
2) Ability to obtain the same surface hardness with a
less drastic quench and, in the case of some of the
alloys, a lower quenching temperature, thus giving less
distortion.
3) Increased toughness, as indicated by the higher
values of yield point, elongation, and reduction of area.
4) Finer grain size, with the resulting higher impact
toughness and increased wear resistance.
5) In the case of some of the alloys, better machining
qualities or the possibility of machining at higher
hardness.
There are generally two types of heat
treated alloy steels:
► Volume hardened steel (or through
hardened steel)
► Case hardened steel
Volume hardened steel (or through hardened steel)
Thru-hardening steels are used when great strength, high
endurance limit, toughness, and resistance to shock are
required. These qualities are governed by the kind of steel and
treatment used. Fairly high surface hardnesses are obtainable in
this group, though not so high as those of the casehardening
steels. For that reason, the resistance to wear is not so great as
might be obtained, but when wear resistance combined with
great strength and toughness is required, this type of steel is
superior to the others. Thru hardening steels become distorted
to some extent when hardened, the amount depending upon the
steel and quenching medium used.
► When the grinding of gear teeth is not practicable and a high
degree of accuracy is required, hardened steels may be drawn or
tempered to a hardness that will permit the cutting of the teeth.
This treatment gives a highly refined structure, great toughness,
and, in spite of the low hardness, excellent wearing qualities.
►
Case hardened steel
Casehardening steels with their extremely hard, finegrained (when properly treated) case and
comparatively soft and ductile core are generally used
when resistance to wear is desired. Casehardening
alloy steels have a fairly tough core, but not as tough
as that of the full-hardening steels.
► But wear resistance combined with toughness, these
steels are more effective, and a same size of properly
case-hardened gear combination can transmit more
torque, compared to a gear pair made of volume
hardened steel.
►
Material of gear/ gearbox generally used in Indian industries
►
►
►
►
Helical gears:
(a) Volume hardened steel (or through hardened steel)
Pinion: EN 19 (Hardened & Tempered), Hardness: 280-320 BHN
Gear: EN 24 (Hardened & Tempered), Hardness: 230-280 BHN
(b) Case hardened steel
Pinion & Gear: SAE 8620 or 17CrNiMo6 or EN 356, Case Hardness: 55 Rc,
Core Hardness: 180-210 BHN
Bevel Gears:
Same as helical gears
Worm Gears:
Worm shaft: C45
Worm wheel: Phosphor Bronze
Housing: CI FG 400 IS 210 or Fabricated (IS 2062)
Modern gear technologists are trying to develop new alloying materials for gears,
to increase gear strength, with compact and reduced size.
► Apart from steels, other materials also used for gears (depending upon
requirement), ie:
Die Cast Alloys, Sintered Powder Metal, Plastics, etc.
►
Gear box lubrication
►
►
►
►
►
►
Gearbox lubrication:
All gears are delivered from manufacturer without oil.
Before start up, the gear should be filled with oil
recommended.
Oil should be filled to oil level indicator.
The oil level should be checked regularly. The checking
must be made while the drive is stationary.
Some times, bearings are normally oil lubricated on
primary side and grease lubricated on secondary side.
Lubrication continued to next page…….
► First
oil change should take place after
running-in period. Drain oil immediately
after stop while oil is still worm. Second oil
change should take place after 200 working
hours. Afterwards, oil change is
recommended after period of 2000-4000
working hours depending on working
conditions.
Lubrication continued to next page…….
► The
oil in the sump carries out lubrication of the
gears and bearings automatically. Units are fitted
with filler, oil level indicator and breather for easy
routine inspection and maintenance. For low speed
application, grease or forced feed lubrication may
be necessary. Maximum heat dissipation is
achieved by means of a radial fan for directing
high velocity air over the cooling ribs of gear case.
For higher capacities, the units are provided with
cooling coils in the lower part of the housing for
allowing cool water passing through a suitable port
entry. With pressure lubrication, oil cooler can be
mounted in the oil circuit to achieve more efficient
and effective cooling.
Gear failure
►
►
►
►
►
►
Causes for gear failure:
Surface fatigue:
(a) Case exfoliation
(b) Initial pitting
(c) Progressive pitting
Scuffing:
(a) Light scuffing
(b) Heavy scuffing
Abrasive wear:
(a) Foreign matter in the lubricant (scoring)
Tooth breakage:
(a) Brittle fracture resulting from high shock load
(b) Excessive loading causing fatigue fracture
Plastic deformation
Smooth chemical wear
Case exfoliation
► It
happens in case of case hardened gears.
Causes:
► Improper case hardening process, causes
uneven case depth. When the gear is
subjected to running conditions, the layer of
hardened case comes out from the soft
core, causing case exfoliation.
Remedies:
► Proper case hardening procedure
► Use of proper lubrication
Tooth Pitting
► Pits
are formed when material is flaked off the
tooth surface near or below the pitch line due to
heavy contact pressure.
► This is the removal of small bits of metal from the
surface, due to fatigue, thereby leaving small
holes or pits. This is caused by high tooth loads
leading to excessive surface stress, a high local
temperature due to high rubbing speeds, or
inadequate lubrication. Minute cracking of the
surface develops, spreads and ultimately results in
small bits breaking out of the tooth surface.
Tooth Pitting
Remedies:
• Avoid high load concentration
• Increase surface strength
• Use a higher viscosity oil
Tooth Scuffing
► These
are due to constantly repeated breakage
of the oil film. It happens due to localised
welding between two meshing teeth.
Remedies:
• Use recommended
viscosity oil
• Provide better cooling
by effective spray
lubrication
• Provide good surface
finish
Tooth Scoring
► This
is a heavy scratch pattern extending from
tooth root to tip. It appears as if a heavily-loaded
tooth pair has dragged foreign matter between
sliding teeth. It can be caused by lubricant failure,
incompatible materials and overload.
Remedies:
• Avoid high load
concentration
• Increase surface
strength
• Use proper lubricant
Tooth breakage
Tooth breakage occurs due to:
► Repeated overloading
► Impact load during meshing
► Uneven distribution of load due to
misalignment of axes
Remedies:
► Increase tooth bending strength
► Proper design of the gear teeth
► Use large chamfer at the end of the tooth
► Proper assembly of the drive system to avoid
misalignment.
Plastic deformation
► Sometimes,
due to over loading, uneven
stress distribution and misalignment, gear
teeth does not break, but it got distorted,
and permanent plastic deformation takes
place.
Remedies:
► Proper hardness of the gear teeth
► Proper design of the gear teeth
► Proper assembly of the drive system to avoid
misalignment.
Smooth chemical wear
Cause:
► Presence of mineral impurities in the
lubricant
Remedies:
► Case harden the teeth
► Use proper and pure lubricant
► Good surface finish
Trouble shooting
Common defects in gearbox:
► Gear heating up
► Gearbox leakage
► Gearbox noise
► Gearbox vibration
► Oil seal whistle
Gearbox heating up
►
►
►
►
►
►
High surrounding temperature may cause heating up
Over loading: If gear box is heating considerably right from
the beginning of its installation, immediate attention
should be paid in the fact whether gearbox was properly
selected, taking into account all the factors under which it
is required to operate.
Use of wrong lubricant: Depending upon the conditions of
working, proper lubricant must be used.
Excessive churning: High viscosity of oil or over filling of
the gearbox will produce excessive churning losses
consequently heating up the gearbox.
Bearing clearance not proper: Improper bearing clearance
may allow the axial floating of shaft and bearing damage.
Misalignment: Misalignment between the shaft of gearbox
and the prime mover and or the driven load causes non
uniform load on bearing and shafts. Whenever possible,
use common base plate for motor and gearbox or else
proper alignment should be done.
Gearbox leakage
► Due
to over filling, the oil level may rise above the
mark and upto the level of oil seal, and there fore
leakage could start.
► Leakage may very rarely take place through joint
faces between top and bottom half or end caps in
which case tightening of bolts and screws will stop
leakage, if not then a fresh layer of good jointing
compound will have to be applied to the joint
faces.
► Any slight damage to the lips of the oil seals due
to wear or misuse could start leakage, in which
case they need to be replaced.
Gearbox noise
Causes of noisy gearbox operation:
► Bearing worn out
► Worn out gears
► Foreign particle in the gearbox, may be
mixed with lubricant
► Excessive backlash
► Tooth contact not proper
► Eccentric running of shaft
►
Proper action to be taken so that, these errors can be
eliminated.
Gearbox vibration
► Vibration
is another area for concern. Solid
foundation and perfect alignment is required
for the gearbox. Couplings should be well
balanced to avoid vibration.
Oil seal whistle
►A
dry condition of oil seal lips, which
allowed to continue, will char and ruin oil
seal lips. Smear the oil seal lips with
lubricant and do not let it remain dry even
when stored for a long time.
Market products and
specification
Specification:
► Type of gearbox
► Transmitted power
► Ratio=Input RPM/Output RPM
► Duty condition
► Type of loading- application
► Type of prime mover
Name of some gearbox manufacturing company
used in Indian Industries:
► New
Allenberry Works
► Greaves
► Elecon
► Shanthi
► Flender
► SEW
► Bonfiglioli
Designation of gearbox
Example:
► Helical/ Bevel-helical Gearbox:
► Make: New Allenberry Works
► Unit brand name: Helimax
C
S
Type of gearbox
CS-Helical
CK-Bevel
C
Number of stage
A-Single stage
B-Double stage
C-Triple stage
D-Quadruple stage
H
Special case
110
Centre distance
H-Foot mounted
(last stage)
hollow output shaft
A-Shaft mounted
hollow output shaft
V-Vertical output shaft
Example:
► Geared motor:
► Make: New Allenberry Works
► Unit brand name: Optimax
Gear unit
Motor unit
R. 93. 52 V
DC 90S 4
Type Size
Size
(only 2
gear casing)
No. of stage No. of stage
Type
Size
No. of poles
►
►
►
►
►
►
Type of gear unit (for geared motor, New Allenberry
make):
R- foot mounted with co-axial or offset output shaft & with
one or two gear casing
RF- flanged type with co-axial or offset output shaft & with
one or two gear casing
R..F-foot cum flanged type with co-axial or offset output
shaft with one or two gear casing
RUF-flanged type with extended hub and shaft and with
co-axial or offset output shaft with one or two gear casing.
Type of motor:
DC-three phase with squirrel cage face mounting motor
DF-three phase with squirrel cage flange mounting motor
Example:
► Worm Gearbox:
► Make: New Allenberry Works
► Unit brand name: Allroyd
S
U
Type of gearbox
SU-Underdriven
SO-Overdriven
SV-Vertical output shaft
M
Metric unit
3
Centre distance (in inches)
For different manufacturer, specification changes; so example given here is only indicative.