DSI Dynamatic AS-703 User manual

1
IM-180001-2019
Eddy Current Air-Cooled Brakes
Model AS-703 through AS-708
INSTRUCTION MANUAL
(AS-703 –AS-708 – Revised 2019)
DRIVE SOURCE INTERNATIONAL INC.
7900 Durand Avenue, Bldg. 3
Sturtevant, WI USA 53177
Toll Free: [phone]
Phone: [phone] - Fax: [phone]
Email: [e-mail]

2
DANGER HIGH VOLTAGE
Motor control equipment and electronic controllers are connected to hazardous line voltage. When servicing
drives and electronic controllers, there may be exposed components with their cases and protrusions at or
above line potential. Extreme care should be taken to protect against shock. Stand on an insulating pad and
make it a habit to use only one hand when checking components. Always work with another person in case
an emergency occurs. Disconnect power whenever possible to check controllers or to perform maintenance.
Be sure equipment is properly grounded. Wear safety glasses whenever working on an electronic controller
or electrical rotating equipment.
CAUTION:
Rototating shafts and above ground electrical potentials can be hazardous. Therefore, it is strongly
recommended that all electrical work conform to National Electrical Codes and local regulations. Installation,
alignment and maintenance should be performed only by qualified personnel.
Factory recommended test procedures, included in the instruction manual, should be followed. Always
disconnect electrical power before working on the unit.
REFER TO OSHA RULES AND REGULATIONS, PARAGRAPH 1910.219 FOR GUARDS ON MECHANICAL
POWER TRANSMISSION APPARATUS.
Note - Since improvements are continually being made to available equipment, the enclosed data is subject
to change without notice. All drawings, unless certified, are for reference only. For additional information,
contact DSI/Dynamatic® at 1-800/548-2169 or 262/554-7977.
IMPORTANT NOTICE
The printed contents in this instruction book are to be used for reference only. Due to periodic engineering
design changes and the addition of modifications, this material is provided as a guide only.
Refer to the enclosed engineering drawings, which are furnished for your specific unit.
For additional information regarding contents of this manual, please send your request to DSI/Dynamatic®,
Fax: [phone], or call: 262/554-7977, or Toll free at 1-800/548-2169.
This notice is provided to clarify the intent of the instruction book contents and to inform our customers how
to obtain appropriate technical assistance from the proper source.
©Copyright DSI/Dynamatic®, 2019

3
Table of Contents
SECTION 1 .......................................................................................................................................5
GENERAL INFORMATION............................................................................................................................................. 5
Introduction .................................................................................................................................................................. 5
Safety........................................................................................................................................................................... 5
Training........................................................................................................................................................................ 5
Receiving and Damage Claims ................................................................................................................................... 5
Handling....................................................................................................................................................................... 6
Storage ........................................................................................................................................................................ 7
SECTION 2 .......................................................................................................................................8
EQUIPMENT DESCRIPTION ......................................................................................................................................... 8
Operation ..................................................................................................................................................................... 8
Cooling......................................................................................................................................................................... 8
Applications ................................................................................................................................................................. 8
Dissipation ................................................................................................................................................................... 9
Maximum Torque Transmitted Through Shaft ............................................................................................................. 9
Construction ................................................................................................................................................................ 9
Tachometer Generator (optional) ................................................................................................................................ 9
SECTION 3 .....................................................................................................................................13
INSTALLATION............................................................................................................................................................. 13
Location ..................................................................................................................................................................... 13
Mounting
.................................................................................................................................................................... 13
Alignment................................................................................................................................................................... 13
Flexible Couplings ..................................................................................................................................................... 13
Parallel Offset Alignment ........................................................................................................................................... 14
Angular Alignment ..................................................................................................................................................... 14
For One Rotating Shaft.............................................................................................................................................. 14
V-Belt Drive Formulas................................................................................................................................................ 16
Bearing Load Calculations......................................................................................................................................... 17
Outline Dimensions.................................................................................................................................................... 18
SECTION 4 .....................................................................................................................................19
MAINTENANCE ............................................................................................................................................................ 19
Cleaning..................................................................................................................................................................... 19
Lubrication ................................................................................................................................................................. 19
Recommended Greases............................................................................................................................................ 19
Bearing Dimensions................................................................................................................................................... 20
SECTION 5 .....................................................................................................................................21
OVERHAUL................................................................................................................................................................... 21
Disassembly/Reassembly ......................................................................................................................................... 21
General ...................................................................................................................................................................... 21
Installation of Bearings .............................................................................................................................................. 21
AB-703 & AB-705 Disassembly
................................................................................................................................. 21
AS-703 & AS-705 Reassembly.................................................................................................................................. 23
AS-704 & AS-706 Disassembly ................................................................................................................................. 23
AS-704 & AS-706 REASSEMBLY ............................................................................................................................. 23

4
Figures & Tables
SECTION 1 .......................................................................................................................................5
Hazard Labels Figure 1-1 ............................................................................................................................................ 6
SECTION 2 .......................................................................................................................................8
Application Data Table 2-1 ....................................................................................................................................... 9
Typical Brake Cutaway Figure 2-1 ............................................................................................................................... 9
G-2 Generator Specifications Figure 2-2 ................................................................................................................... 10
Alnico Stator Lamination Assy. Figure 2-3................................................................................................................. 10
Speed/Torque Curve – Model AS-703 Figure 2-4 ..................................................................................................... 11
Speed/Torque Curve – Model AS-704 Figure 2-5 ..................................................................................................... 11
Speed/Torque Curve – Model AS-705 Figure 2-6 ..................................................................................................... 11
Speed/Torque Curve – Model AS-706 Figure 2-7 ..................................................................................................... 12
Speed/Torque Curve – Model AS-707 Figure 2-8 ..................................................................................................... 12
Speed/Torque Curve – Model AS-708 Figure 2-9 ..................................................................................................... 12
SECTION 3 .....................................................................................................................................13
Misalignments Figure 3-1........................................................................................................................................... 14
Permissible Operating Misalignment* Table 3-1 .................................................................................................... 15
Allowable Overhung Load at Center of StandardShaft Keyway1Table 3-2 .......................................................... 15
Allowable Overhung Load ......................................................................................................................................... 15
Reactive Force Figure 3-2 ......................................................................................................................................... 16
Arc of Contact Correction Factors G and R Table 3-3 ........................................................................................... 17
Allowable Sheave Rim Speed* Table 3-4 .............................................................................................................. 17
Overhung Sheave Figure 3-3..................................................................................................................................... 17
Outline Drawings Figure 3-4 ...................................................................................................................................... 18
SECTION 4 .....................................................................................................................................19
Grease Locations Figure 4-1.................................................................................................................................. 19
Recommended Greases Table 4-1 ........................................................................................................................ 20
Bearing Dimensions Figure 4-2 ................................................................................................................................. 20
Dimensions – Inches Table 4-2.............................................................................................................................. 20
SECTION 5 .....................................................................................................................................21
Typical Cross Section Drawing – AS-703 Figure 5-1................................................................................................. 22
Model AS-703 Parts List Table 5-1 ........................................................................................................................ 22

5
SECTION 1
GENERAL INFORMATION
Introduction
This instruction manual provides general
information and operating instructions for
Dynamatic standard foot mounted, eddy-current
air-cooled brakes, AS-703 through AS-708.
However, where specific differences do exist,
separate instructions and data are provided.
Whether this manual is to be used for standard or
special units, the exact assembly drawing and
contract specifications should be considered when
following these instructions. This manual can also
be used for non-standard units. However, separate
supplement sheets will be provided to cover any
special aspects requiring instructions.
While every effort has been made to provide a
complete and accurate manual, there is no
substitute for trained, qualified personnel to handle
unusual situations. Any questions that arise should
be referred to DSI/Dynamatic®, Fax: 262-554-
7041, or call: 262/554-7977, or Toll free at 1-
800/548-2169.
Safety
Electrical rotating equipment and associated
controls can be dangerous. Therefore, it is
essential that only trained, skilled personnel be
allowed to work with this equipment, under
competent supervision. The danger is increased
when the equipment is not handled, installed,
maintained or used properly.
Read appropriate sections of this manual before
beginning work. Become especially familiar with all
safety instructions and procedures. Heed any
hazard labels on the equipment and be sure to
instruct others in their meaning and importance.
The various types of labels used to alert personnel
of hazards and their degree of hazard potential are
as follows:
DANGER: Used to call attention to an immediate
hazard, where failure to follow instructions could
be fatal.
WARNING: Identifies hazards having possibilities
for injury to personnel.
CAUTION: Used to warn of potential hazards and
unsafe practices.
INSTRUCTION NOTE: Used where there is a
need for special instruction relating to safety,
proper operation or maintenance.
See Figure 1-1 on the following page for examples
of the hazard labels that may appear on this
equipment. Study them carefully; they are put on
the unit for safety. Acquaint maintenance and
operating personnel with their appearance and
content.
Training
Training programs are an essential part of safe and
correct operation. Training provides the know-how
necessary to obtain top performance from your
equipment. DSI/Dynamatic®
recognizes this fact and conducts training schools
to educate your plant personnel in safe
maintenance and operating procedures. Training
schools can be scheduled by contacting
DSI/Dynamatic®. There is a charge for this service.
Special training schools structured around your
specific equipment can also be arranged.
Receiving and Damage Claims
This equipment is assembled and tested prior to
shipment to make sure it functions properly. After
testing, the unit is carefully packed for shipment,
using approved packaging methods. The carrier, in
accepting the shipment, agrees that the packing is
proper and assumes the responsibility for safe
delivery.
Although every precaution is taken to assure that
your equipment arrives in good condition, a careful
inspection should be made on delivery. Check all
items against the packing list to be sure

6
Hazard Labels Figure 1-1
the shipment is complete; then carefully inspect for
damage. Any evidence of rough handling may be
an indication of hidden damage.
Note - Shipping damages are not covered by the
warranty; the carrier assumes responsibility for
safe delivery. If you note damage or missing items,
IMMEDIATELY file a claim with the carrier. At the
same time, notify DSI/Dynamatic®. If assistance is
needed to settle a claim, contact the factory. To
expedite this service, refer to your equipment by
purchase order, Model, Pro and Serial Numbers.
The following check list is included-to assist with
the receiving inspection.
1. Inspect the packaging, covering and
skid for signs of mistreatment.
2. Inspect the housing to make sure there is no
damage.
3. Manually rotate shaft to be sure it is free from
binding and noise.
4. Check for moisture and foreign material in
the unit, especially on electrical windings,
around the shaft and bearing caps and in
accessories.
Handling
Only skilled personnel, following standard
safety practices, should handle this
equipment. Avoid jarring or pounding on shaft.
Do not attempt lifting by the shaft. Handling is
best accomplished with a fork lift or crane.
When using a fork lift, be sure the unit is well
supported, with the forks adequately spread and
centered under the skid.
The units can also be lifted by a crane. To avoid
damage, attach the crane cables to all eye bolts
provided on the unit.
Units mounted on a common base with other
equipment may be lifted with a suitable sling under
the base or by attaching cables to eye bolts
designed and installed into the base for lifting the
complete assembly. Refer to the certified drawings.
Do not use the eye bolts on the unit if the unit is
attached to another piece of machinery or gear box,
unless the drawings show they were designed for
lifting the assembly. When two or more cables are
used, maintain a near-vertical pull on the eye bolts.
If near-vertical pull is not possible, use a spreader
bar to take side pull off of the eye bolts.
Storage
Whenever this unit is to be set aside in storage, a
clean, dry area must be provided, and it should be
kept in its original crate. If kept in an air tight
material such as polyethylene, silica-gel or some
other moisture absorbent should be used to
prevent rust. Additional grease is not required until
ready for operation. Shaft should be rotated
occasionally to redistribute bearing grease and to
prevent bearings from becoming brinelled.

7
SECTION 2
EQUIPMENT DESCRIPTION
Operation
Eddy-current brakes consist basically of a rotating
member keyed to a straight through shaft and a
stationary field assembly. The shaft is supported by
an anti-friction bearing in each end bell. An air gap
exists between the smooth surface of the rotor and
the pole, or segmented surface, of the stationary
field assembly.
Until the field coil is energized, the brake rotor
revolves at the speed of the prime mover. When the
field coil is energized, a magnetic flux is established
between the poles, or teeth. As the rotor revolves,
magnetic lines of force are cut in the air gap and
eddy-currents are generated which in turn retard
rotation at a rate determined by the amount of
excitation applied to the field coil. Braking torque is
a function of speed and field coil excitation. By
regulating this excitation, which is infinitely
adjustable with Dynamatic controllers, control of
brake torque is easily accomplished. The
Speed/Torque relationship, with constant
excitation, is illustrated in the torque curves. Eddy-
current brakes cannot be used for holding functions
because there is zero torque at zero slip.
Heat resulting from the torque produced with
excitation up to 30% of the hot coil amperage rating
for the brake can satisfactorily be cooled. Constant
excitation exceeding this value produces heat in
excess of the cooling capacity of the brake,
resulting in overheating and seizure of the brake
rotor. Brakes operated within this limitation can be
expected to provide many years of trouble- free
service.
Cooling
Energy absorbed by the brake is converted to heat
and dispelled by air drawn over the heat producing
surfaces. Vanes on the rotating fan are designed to
draw sufficient cooling air into the brakes through
the screened openings to dissipate heat in
accordance with the brake ratings. Fins cast into
the rotor present an even greater heat-dissipating
area to the flow of cooling air.
Applications
Caution When Continuous Loading
Regardless of speed, the amount of continuous
torque that can be applied must not exceed a
recommended safe value which is obtained with
approximately 30% of the coil amperage rating of
the brake. Continuous excitation in excess of this
amount will cause overheating and seizure of the
brake rotor. Attention to this important detail may
save you expensive and time-consuming repairs.
Use of the Dynamatic brake to impose a controlled
load on a wound rotor motor is an ideal means of
accurately controlling the lifting and lowering
functions of cranes and hoists. The combination of
Dynamatic brake and wound rotor motor can also
be the solution to other applications requiring
closely controlled speed. Simulating test loads for
drive line components is another application. They
-can also be used for conveyor brakes & controller.

8
Application Data Table 2-1
Data Slip RPM
Brake Model No.
AS-703
AS-704
AS-705
AS-706
AS-707
AS-708
Maximum Torque
Lb. Ft.
1800
1200
900
53
49
43
110
99
90
210
204
195
420
410
388
-
870
870
-
1740
1740
Dissipation
3600
10
20
Maximum
1800
7.5
15
20
35
60
100
Continuous
1200
5
10
15
25
45
75
Horsepower
900
3.5
7.5
11.5
17.5
34
56
Inertia - Lb. Ft.
0.82
1.64
8.0
16.0
50
100
Size controller
1
2
2
3
3
7
Approximate Shipping
108
205
265
430
1010
1200
Maximum Torque Transmitted Through Shaft
(Standard Brakes Only)
AB-703 - 340 lbs. ft. AB-
704 - 563 lbs. ft. AB-705 -
860 lbs. ft. AB-706 - 1258
lbs. ft. AB-707 - 1749 lbs.
ft. AB-708 - 3103 lbs. ft.
Note - Numbers apply only when there is no
overhung load - consult factory for data with
overhung load.
Typical Brake Cutaway Figure 2-1
Construction
A single field and rotor type brake as illustrated in
Figure 2-1 is representative of Models AS-703, AS-
705, and AS707. Models AS-704, AS-706
and AB-708 are of the double field and rotor
type which include two rotors, fans and field
assemblies.
Tachometer Generator (optional)
General
The generator is a permanent-magnet, alternating-
current device that produces a linear voltage in
direct proportion to the speed at which it is driven.
In the governing circuit of the control system, the
voltage produced by the generator represents the
actual speed of the unit. This voltage is amplified
and compared with a constant voltage in the
reference circuit, representing the desired speed of
the unit, to effect speed control.
As shown in Figure 2-2, the maximum output speed
of the generator is approximately 55 to 60 volts.
Frequency varies with the speed to a maximum of
500 to 600 Hz. This generator is designed to
operate with equal output and efficiency in either
direction of rotation.
The use of an AC tachometer generator eliminates
rotating windings and consequently no
maintenance of brushes, slip rings, or commutator
is required.
The Alnico magnet employed in this unit (Figure 2-
3) retains its field strength over a long period of
time, assuring a constant generator output at a
given speed. This magnet should not be subjected
to sharp impacts, abuse, or temperatures higher
than the maximum operating temperature of the
unit, as this will result in a weakening of the field
strength. Should removal of

9
G-2 Generator Specifications Figure 2-2
the magnet be necessary for remagnetization or
repairs, the entire operator assembly should be
returned to the factory.
Description
The generator if used, is a separately mounted type
generator that is contained within its own housing
and is driven by appropriate pulleys and belts from
the shaft.
A specific volts per RPM is not essential. Correct
adjustment of the controller (see your operating
instructions) Alnico Stator will compensate for wide
variance in generator output.
Alnico Stator Lamination Assy. Figure 2-3

10
Speed/Torque Curve – Model AS-703 Figure 2-4
Speed/Torque Curve – Model AS-704 Figure 2-5
Speed/Torque Curve – Model AS-705 Figure 2-6

11
Speed/Torque Curve – Model AS-706 Figure 2-7
Speed/Torque Curve – Model AS-707 Figure 2-8
Speed/Torque Curve – Model AS-708 Figure 2-9

12
SECTION 3
INSTALLATION
Location
Select a permanent location affording an
unobstructed flow of clean cooling air to permit the
unit to perform according to its ratings. Locate the
unit at least 12 inches away from walls and similar
obstructions to ensure sufficient air for cooling. The
ambient temperature of input air must not exceed
40°C. (104°F.). Higher ambient temperatures
reduce the thermal rating by 20 percent for every
7°C. (20°F.) ambient increase. Maximum ambient
must not exceed 66°C. (150°F.).
Mounting
The unit should be mounted directly to a bed, base
or platform to ensure that it is rigid. Even if it is
purchased mounted on a base, the base must still
be aligned and secured.
CAUTION: Failure to properly mount and level this
unit may result in distortion to the housing,
mechanical failure, misalignment and rapid bearing
wear.
Mount the unit as follows:
1. One or more mounting feet of the unit may not
contact their mounting pads. With a feeler
gauge, find and measure gap between each
foot and its pad.
2. Place slotted shim, equal in thickness to
measured gap, under each high mounting foot.
3. Install mounting bolts or nuts finger tight.
4. Proceed with alignment as described below
under "Alignment".
5. Alternately tighten bolts.
6. Recheck alignment and change shims as
required.
7. Dowel all directly connected units to prevent
creeping and future misalignment.
Alignment
General
Proper installation and alignment of this unit,
as specified herein, is a condition of the
Manufacturer's warranty.
Angular misalignment and Offset misalignment
between directly connected shafts will cause
increased bearing loads and vibration, even when
the connection is made by means of a flexible
coupling. Shaft alignment becomes especially
critical if operated at high speeds. For this reason,
the alignment of directly connected shafts must be
checked with a dial indicator after coupling hubs
have been installed.
Flexible Couplings
A flexible coupling should be used to connect inline
shafts in order to avoid undue bearing stresses. It
should never be forced onto a shaft by pounding,
or serious damage to the bearings is risked.
Moderate heat can be applied to the hubs to locate
them in place on the shafts. If the hubs must be
pressed on, use the threaded hole in the end of the
shaft in order to avoid bearing damage. Be careful
to start it true, not cocked, otherwise it is possible
to burr the shaft. A light film of oil or other lubricant
on the shaft will prove an aid to mounting. Be sure
that the shafts are well cleaned before the coupling
hubs are installed. When pressed over a
considerable length of shaft, it may be necessary
to expand the coupling hubs by heating.
CAUTION: DO NOT drive or force the coupling hubs
onto the shafts.
If a key is used in a coupling, be sure that the key
fits snugly in the shaft and coupling but does not fill
the space on top of the key. Some clearance must
be left at this point.
Note - Although flexible couplings are designed to
accommodate parallel and angular misalignment, care
should be taken to align the driving and driven
machinery as accurately as possible when the coupling
is installed. Even when the original alignment has been
very accurate, misalignment

13
may occur later because of settling foundation,
wear of bearings, etc., and it is well to make
periodic checks to see that such misalignment does
not become excessive.
Parallel Offset Alignment
Offset misalignment is illustrated in Figure 3-1. Also
shown is the location of the dial indicator. Offset
alignment can be accomplished as follows:
1. Clamp the dial indicator on the hub and position
the finger on the ground or machined diameter
of the other hub (Figure 3-1, Item 1).
2. Scribe a mark on the surface of the hub where
the finger is located.
3. Rotate both shafts simultaneously while
keeping the finger on the scribe mark. Note the
readings at each 1/4 revolution.
Misalignments Figure 3-1
Note - Refer to Table 3-1 for permissible parallel
offset misalignment.
Angular Alignment
Angular misalignment is illustrated in Figure 3-1.
Also shown is the location of a dial indicator.
Angular alignment can be accomplished as follows:
1. Clamp the dial indicator on the hub and position
the finger on the other hub face (Figure 3-1, Item
2).
2. Scribe a mark on the face of the hub where the
finger is located.
3. Rotate the shaft and note the dial indicator
reading for a measurement of the angular
misalignment per Table 3-1.
Note - Refer to Table 3-1 for permissible angular
misalignment.
For One Rotating Shaft
If it is impossible to rotate both shafts, the dial
indicator should still be used by following this
procedure for both angular and offset alignment:
1. Clamp the dial indicator to the rotating shaft.
2. Position the finger against the face of the
other hub (Figure 3-1).
3. Rotate the shaft and note the dial indicator
reading for a measurement of the angular
misalignment per Table 3-1.
4. Position the finger against the diameter of the
other hub.
5. Rotate the shaft and note the dial indicator
reading for a measurement of offset
misalignment per Table 3-1.

14
Permissible Operating Misalignment* Table 3-1
Model
AS-
Basic
Coupling
Size
In.
Parallel
Offset

X, In.
Angular

Y, In./In.
Radius
Maximum Angular
with a Measured
Parallel Offset
In./In. Radius**
703
704
705
706
707
708
1.50
2.00
2.00
2.50
2.50
3.00
.0050
.0100
.0100
.0100
.0100
.0120
.0040
.0058
.0058
.0052
.0052
.0064
Y = .0040- .8 X 
Y = .0058- .6 X 
Y = .0058- .6 X 
Y = .0052- .5 X 
Y = .0052- .5 X 
Y = .0064- .5 X 
*Operating misalignment depends on the following factors: Initial misalignment, temperature growth and foundation settlement. Initial
alignment should allow for the effects of temperature growth and foundation settlement. All above values are (TIR) Total Indicator
Runout. To avoid errors in readings due to shaft magnetism, non-magnetic indicators should be used.
**Maximum value for either must not exceed those given in columns 3 and 4.
Allowable Overhung Load at Center of Standard Shaft Keyway1Table 3-2
RPM
Brake Model No
AS-703
AS-704
AS-705
AS-706
AS-707
AS-708
3600
360
410
-
-
-
-
1800
460
525
570
640
1720
1810
1200
530
605
655
750
2000
2130
900
585
660
720
825
2200
2360
1The overhung load values are pounds of weight at the center of a standard shaft keyway and perpendicular
to the shaft axis. The calculations are based on a minimum of 15,000 hours of bearing life for 90% of the
bearings. For 20,000 hours of bearing life, use 91% of the loads given.
Rough Check
The unit can be roughly aligned without the use of
a dial indicator, but alignment as such is not
recommended for permanent installations. The
degree of angular misalignment can be roughly
determined by inserting feeler gauges between
faces of the coupling hubs. The amount of offset
misalignment can be roughly determined by
positioning a straight edge across the machined
diameter of the hubs.
Allowable Overhung Load
If this unit is to be belt or chain driven, reference
must be made to the allowable overhung load, per
Table 3-2.
Table 3-2 lists the maximum force in pounds that may
be applied radially at the center of the output shaft
keyway. If a sheave or sprocket is to be
installed on a new shaft the resultant load which is
imposed by the belt or chain must not exceed the
allowable limit at the speeds specified in the Table.
"P" in Figure 3-2 represents the pull produced in a
chain or belt and is a direct function of the torque of
the driving sprocket or sheave. "R" represents the
normal, reactive force imposed on the shaft and is
equal to "P" plus the tension required to prevent
slipping of the belt.
When chain and sprocket drives are used, the
reactive force "R" will be approximately equal to "P",
since no additional tension is required in a chain for
an effective transmission of power. However, if "V"
belts are used, the reactive force "R" will be
approximately 1.5 times the value of "P" because of
the belt tension required to prevent the belts and
sheaves from slipping. With flat belts and sheaves,
"R" will be 2.5 to 3 times

15
"P", depending on the size of the sheaves, since
smaller sheaves require tighter belting. Belting
strains imposed on the shaft of this unit should
never be greater than the amount required to
prevent slipping of the sheaves.
Reactive Force Figure 3-2
V-Belt Drive Formulas
In cases where tensioning of a drive affects belt pull
and bearing loads, the following formulas may be
used for calculations.
T1– T2= 33,000 (HP)
V
Where: T1= tight side tension, lbs.
T2= slack side tension, lbs.
HP = design horsepower
V = belt speed, FPM
T1+ T2= 33,000 (2.5 - G) (HP)
GV
Where: T1= tight side tension, lbs.
T2= slack side tension, lbs.
HP = design horsepower
V = belt speed, FPM
G = arc of contact correction factor*
T1/T2= 1
1 – 0.8 G
(Also, T1/T2= eKO)
Where: T1= tight side tension, lbs.
T2= slack side tension, lbs.
G = arc of contact correction factor*
e = base of natural logarithms
K = .51230, a constant for V-belt dive
design
O = arc of contact in radians
T1= 41,250 (HP)
GV
Where: T1= tight side tension, lbs.
HP = design horsepower
V = belt speed, FPM
G = arc of contact correction factor*
T2= 33,000 (1.25 - G) (HP)
GV
Where: T2= slack side tension, lbs.
HP = design horsepower
V = belt speed, FPM
G = arc of contact correction factor*
V = (PD) (rpm) = (PD) (rpm) (.262)
3.82
Where: V = belt speed, FPM
PD = pitch diameter on sheave or
pulley
rpm = revolutions per minute of the
same sheave or pulley
*Arc of contact correction factor G and R; see
Table 3-3.

16
Arc of Contact Correction Factors G and R Table 3-3
D-d
C*
Small Sheave
Arc of
Contact
Factor
G
Factor
R
D-d
C*
Small Sheave
Arc of
Contact
Factor
G
Factor
R
.00
180°
1.00
1.000
.80
133°
.87
.917
.10
174°
.99
.999
.90
127°
.85
.893
.20
169°
.97
.995
1.00
120°
.82
.866
.30
163°
.96
.989
1.10
113°
.80
.835
.40
157°
.94
.980
1.20
106°
.77
.800
.50
151°
.93
.968
1.30
99°
.73
.760
.60
145°
.91
.964
1.40
91°
.70
.714
.70
139°
.89
.937
1.50
83°
.65
.661
*D = diameter of large sheave; d = diameter of small sheave; C = center distance.
Bearing Load Calculations
To find actual bearing loads it is necessary to know
machine component weights and values of all other
forces contributing to the load. Sometimes it
becomes desirable to know the bearing load
imposed by the V-belt drive alone. This can be
done if you know bearing spacing with respect to
the sheave center and shaft load (see Figure 3-3)
and apply it to the following formulae:
Load at B, Lbs. = Shaft Load (a+b)
A
Load at A, Lbs. = Shaft Load (b)
a
Where: a and b = spacing, inches
Allowable Sheave Rim Speed* Table 3-4
Sheave Material
Rim speed in feet per
minute
Cast iron
Ductile Iron
Steel
6,500
8,000
10,000
*These rim speed values are maximum for normal
considerations. In some cases, these values may
be exceeded. Consult factory and include complete
details of proposed application.
Overhung Sheave Figure 3-3

17
Outline Dimensions
Outline Drawings Figure 3-4
AII models, except AB-707, are furnished with a water-tight junction box; customer must drill opening where
desired.
Tolerance for 1.50 in. and smaller shafts is +1000/-.0005; for more than 1.50 in. it is +000/-.001

18
SECTION 4
MAINTENANCE
Cleaning
Cleaning should be performed as often as dictated
by the environment of the unit. The
more severe (dirty or hot) the conditions are, the
more often these tasks must be performed. Before
doing any work, be sure the unit is turned OFF and
the AC power is locked out.
Clean accumulated dust and dirt from the unit and
immediate area. Pay special attention to air intake
areas in end bells. Dirt allowed to accumulate there
can easily obstruct air flow or be drawn into the unit
to cause overheating or mechanical binding.
Since the brake is open, internal cleaning may
occasionally be required. The frequency depends
on existing conditions. Oil or coolants in the air are
drawn into the unit. If this occurs, disassemble
brake. Solidly packed dirt, grease and oil should be
cleaned using a high-flash safety solvent. Wipe
with solvent dampened cloth or use a soft bristled
brush. Do not soak the electrical windings. Oven
dry electrical windings at 65°C. (150°F.).
Lubrication
Units equipped with ball bearings were sufficiently
lubricated at the factory to require no further
lubrication for 2,000 hours, if operated under
reasonably normal conditions in an area free of
acid fumes, excessive humidity, dust, dirt or any
foreign matter harmful to bearings and lubricant.
Operating conditions and atmospheric conditions
existing in the area of installation must be
considered when determining how often lubrication
is necessary. If operating under favorable
conditions that do not warrant frequent lubrication,
the grease inlets would be equipped with plugs that
are replaced with grease fittings only during
lubrication. Refer to Figure 4-1.
Allow only experienced maintenance personnel to
lubricate this unit. Before lubricating refer to your
specific assembly drawing to determine the specific
type and location of bearings that are used. The
following steps constitute the procedure for
lubricating ball bearings:
1. Clean the exterior of the unit around the
grease and drain plugs.
2. Remove the drain plugs and if grease holes are
plugged, remove the plugs and install grease
fittings in their place.
3. Slowly introduce grease into the bearings until
clean grease appears at the drain holes.
4. Before replacing the drain plugs operate the
unit for approximately 15 minutes to expel any
excess grease from the bearing chambers.
Then wipe off all grease from around drain
holes and grease fittings. 'Replace the drain
plugs.
5. If the unit is being operated under reasonably
normal conditions, and does not require
frequent lubrication, replace grease fittings with
plugs as a precaution against personnel over-
lubricating bearings.
Grease Locations Figure 4-1
Recommended Greases
The grease specification is per DSI/Dynamatic®
Engineering Standards MML 4-1.2. This is a
general-purpose industrial grease, NLG1 #2 grade,
mineral oil in a lithium-based carrier.
Table 4-1 is a list of products that comply with the
Dynamatic specifications.

19
Recommended Greases Table 4-1
Company
Grease
Shell
Gulf
Texaco
Mobil
Alvania #2
Gulfcrown #2
Multifak #2, Premium
RB, Regal AFB 2
Mobilux #2
Bearing Dimensions Figure 4-2
Bearing Dimensions
Dimensions – Inches Table 4-2
Bearing
AB-703,
AB-704
AB-705,
AB-706
AB-707,
AB-708
A
Shaft O.D.
1.7722
1.7717
2.1660
2.1654
3.1502
3.1497
B
End Bell
Bore
3.3465
3.3473
3.9370
3.9378
6.6929
6.6939

20
SECTION 5
OVERHAUL
Disassembly/Reassembly
General
Read these instructions carefully and check the
appropriate typical Cross Section Drawing with
your own assembly drawing to determine the extent
of disassembly that is necessary to remove
bearings, applying force only to the inner race when
removing from a shaft.
Match mark all parts before removing to aid in
reassembly.
When reassembling the unit, the use of new
bearings is recommended. After all machine fits
have been checked, repaired or replaced, proceed
with reassembly.
Installation of Bearings
Bearings should never be forced onto a shaft or into
a housing by blows applied to either race. To do so
is to risk serious damage to the bearings. Use
either an arbor press, or a jack and a piece of soft
metal tubing squared on both ends, if necessary.
Be careful to start the bearing true, not cocked;
otherwise it is possible to burr the shaft. A light film
of oil or other lubricant on the shaft will prove an aid
to mounting. Be sure that the shaft and bearing
bores are well cleaned before the bearing is
installed. Also, the mechanic doing the work should
be careful that particles of metal or other foreign
matter do not enter the bearing during installation.
Do not unwrap bearings until ready for installation.
When a bearing is to be pressed over a
considerable length of shaft, or over a tight-fitting
seat, it may be necessary to expand the bearing by
heating in oil. When a bearing is heated in oil, the
temperature of the oil should not exceed 93°C.
(200°F.) and the bearing should not be kept in the
bath longer than necessary to bring the entire
bearing to the required temperature.
AB-703 & AB-705 Disassembly
1. Remove unit from operation and pull off shaft
coupling hubs, or sheaves, with approved
bearing puller and remove shaft key(s) (1).
2. Remove junction box cover by removing two
screws. Disconnect brake leads inside of
junction box.
3. Remove four cap screws and lockwashers (2)
from field assembly (3) and slide entire field and
shaft assembly out of housing (4). Slide field
assembly off of bearing.
4. Using an approved bearing puller, remove
bearing (5) from each end of shaft (6). Force
should be applied only to the inner race when
removing bearing.
5. If necessary, remove bolts holding the coil to
the field assembly after match marking, being
careful not to scrape insulation off of coil Ieads.
6. If necessary, remove snap ring (7), fan (8) and
key (9) from the shaft; heat hub of fan if
necessary.
7. Clean all pieces of grease and dirt before
reassembly.