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TRASCO® ESbacklash-free couplings
®
Ringfeder Corporation
RINGFEDER Products are available from MARYLAND METRICSP.O. Box 261 Owings Mills, MD 21117 USA email: [email protected] web: http://mdmetric.com
The TRASCO® ES consists of two hubs, made of high-strengthaluminum (up to the 38/45 size) or steel (from size 42) that areconnected with an elastic element.
The hubs are made by accurate machining, in order to achieveaccuracy, balance and optimal concentricity.
The spiders are made of a special polyurethane mixture that wasdeveloped after considerable research and laboratory testing.They are press-formed by a process which guarantees a highdegree of dimensional accuracy.
The spiders are available in different hardnesses: 92 Sh. A (yel-low), 98 Sh. A (red), 64 Sh. D (green), 80 Sh. A (blue).
Coupling performance depends on the type of spider selected(see “Technical data” ).
Other hardnesses are available on request to meet special ope-rating conditions, such as higher temperatures, higher torques,and higher degree of vibration-damping capability.
When the polyurethane element is installed in the precisionmachined hub it becomes precompressed, thereby providingthe zero backlash feature which characterizes the transmissionperformance of this coupling.
The coupling remains torsionally rigid (and backlash free) withinthe range of the pre-compression load, while permitting the
absorption of radial, angular and axial misalignments as well asundesired vibrations.
The significantly wide pre-compressed area of the flexible ele-ment keeps the contact pressure low against the elastic ele-ment. Therefore, the spider’s jaws, can be overloaded manytimes without losing original properties.
HUBS
ELASTIC ELEMENT
The main design function of the TRASCO® ES coupling is to transmit motion while absorbing misalignments and vibrations,with absolute precision and without any backlash whatsoever. The very compact design makes it a very rational and functional
device ideal in every positioning or feedback application.Ringfeder
Ringfeder Corporation
2
• Backlash free torque transmission• Vibration dampening • Low inertia• Easy and time saving assembly• Maintenance free• High speed performance• Electrical isolation
In all positioning and feedback applications, smaller TRASCO®
ES couplings (up to size 19/24) replace successfully bellows,oldham, metallic beam and disc couplings. Larger TRASCO® ES
couplings (from size 24/28) replace successfully metal disc,rigid, steel gear and beam coupling in spindle drives, processline drives and other high torque drive applications.
Advantages
– Encoders– Steppers– Pulse generators– Tachometers– Medical equipment– Robotics– Servos– Ball screws– Machine tools spindles– Process lines
Main applications
The recommended operating temperature range for the TRA-SCO® ES is between –40 and +90°C. Peak temperatures as highas 120°C can be tolerated.Higher operating temperatures may cause the spider to lose aconsiderable amount of elasticity, thus substantially lowering thetorque capacity.Therefore, when selecting a coupling, the operating temperatu-re must be carefully considered. (see “Selection”)
Operating Temperature RangeT [°C]
Torsion angle [ rad]
Item code examples:
TRASCO® ES HubClamping hub Type (without keyway)Hub SizeBore ¬
ES SpiderSpider Size and Color (R = red, G = yellow, V = green, B = blue)
GES M 24/28 F20
AES 24/28 R
T [°C]
Torsion angle [rad]
Ringfeder Corporation
RINGFEDER Products are available from MARYLAND METRICSP.O. Box 261 Owings Mills, MD 21117 USA email: [email protected] web: http://mdmetric.com
Standard TypeThe hubs of the standard coupling type can be either solidor have a finished bore, the diameter of which correspondsto any one of the standard shaft diameters.
Both the solid hub and bored hub coupling are generallyavailable from stock for quick delivery.
from size 7 to 14 from size 19/24 to 38/45 from size 42
Mass moment*of inertia (J)
Size F min F max a A G L I M N s p c tWeight*
[kg] .003
[lbs] .007
[kg] .009
[lbs] .020
[kg] .020
[lbs] .044
[kg] .075
[lbs] .165
[kg] .154
[lbs] .339
[kg] .253
[lbs] .558
[kg] .455
[lbs] 1.003
[kg] 1.720
[lbs] 3.784
[kg] 2.390
[lbs] 5.258
[kg] 3.800
[lbs] 8.360
[kg] 4.500
[lbs] 9.900
7[mm]
[inch]
9[mm]
[inch]
14[mm]
[inch]
19/24[mm]
[inch]
24/28[mm]
[inch]
28/38[mm]
[inch]
38/45[mm]
[inch]
42[mm]
[inch]
48[mm]
[inch]
55[mm]
[inch]
65[mm]
[inch]
3
.12
4
.16
4
.16
6
.24
8
.31
10
.39
12
.47
14
.55
15
.59
25
.98
25
.98
7
.28
9
.35
14
.55
24
.94
28
1.10
38
1.50
45
1.77
42
1.65
48
1.89
70
2.76
75
2.95
–
–
–
–
–
–
–
–
–
–
–
–
–
–
75
2.95
85
3.35
110
4.33
115
4.53
14
.55
20
.79
30
1.18
40
1.57
55
2.17
65
2.56
80
3.15
95
3.74
105
4.13
120
4.72
135
5.31
–
–
7.2
.28
10,5
.41
18
.71
27
1.06
30
1.18
38
1.50
46
1.81
51
2.01
60
2.36
68
2.68
22
.87
30
1.18
35
1.38
66
2.60
78
3.07
90
3.54
114
4.49
126
4.96
140
5.51
160
6.30
185
7.28
7
.28
10
.39
11
.43
25
.98
30
1.18
35
1.38
45
1.77
50
1.97
56
2.20
65
2.56
75
2.95
8
.31
10
.39
13
.51
16
.63
18
.71
20
.79
24
.94
26
1.02
28
1.10
30
1.18
35
1.38
6
.24
8
.31
10
.39
12
.47
14
.55
15
.59
18
.71
20
.79
21
.83
22
.87
26
1.02
1.0
.04
1.0
.04
1.5
.06
2.0
.08
2.0
.08
2.5
.10
3.0
.12
3.0
.12
3.5
.14
4
.16
4.5
.18
6
0.24
1.5
.06
2
.08
3.5
.14
4
.16
5
.20
5
.20
5
.20
5
.20
5
.20
5
.20
M3
M3
M4
M5
M5
M6
M8
M8
M8
M10
M10
3,5
.14
5
.20
5
.20
10
.39
10
.39
15
.59
15
.59
20
.79
20
.79
22
.87
22
.87
ALUMINIUM HUBS
STEEL HUBS
* Value refers to single hubs with max bore. Bore tolerance: H7.
Hub
Ringfeder Corporation
From size 7 to 19/24: single slot execution. From size 24/28 to 65: double slot execution.
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M Type (with clamping hubs)This type of coupling provides a quick, backlash-free hub toshaft connection.To achieve the torque values shown, the socket head cap screw
tightening torque (Ms), must be respected.The M coupling type is available with or without keyway.
A Type (shrink disc execution)It has been designed for high torque applications such asmilling and grinding spindles, ball screws and it is ideal forhigh speed machining applications.The special shrink disc design, allows blind mounting and
an extremely easy and time saving assembly.To achieve the torque value shown, the screws tighteningtorque (Ms) must be respected.
Made in steel, in 10 sizes, it is the ideal coupling for high speed applications (up to 60 m/s) such as milling spindle onmachining centers as well as for multi spindles applications.
With peripheral speeds exceeding 30 m/s, dynamic balancing is recommended. This can be done on request.
* at 0.5 of Tkn
Size Spider
7
9
14
19/24
24/28
28/38
38/45
42
48
55
65
92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)64 Sh. D (green)92 Sh. A (yellow)98 Sh. A (red)
TRASCO® ES couplings compensate for axial, radial and angu-lar misalignments, caused by heat extension, tolerances.Even after operating for an extended time period with a misa-lignment, there is still zero backlash because the elastic ele-ment is only stressed by pressure loads.
When an application causes a high degree of misalignment, adouble cardan design can be supplied.
Due to its superior design, the TRASCO® ES coupling offer sim-ple and time saving assemblies. Blind and detachable mountingis also possible.
Shaft should be carefully cleaned.
While mounting the coupling it is important to respect the “s”dimension to guarantee optimal misalignment capability as wellas to assure electrical isolation.To reduce the assembling axial force it is possible to lubricatethe elastomer spider’s jaws.
Shrink disc hubs (execution “A”)
Once the hub is installed on the shaft, the screws must betightened uniformly and crosswise to the indicated tighteningtorque (Ms).
To dismantle unscrew all bolts, insert the screws in thedismounting threaded holes and tighten gradually until the hubis released.The cone surface of the shrink disc hubs are greased at thefactory to guarantee superior performances.
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Tkn Nominal torque
Tkmax Maximum torque
CT stat. Static Torsional Rigidity
CT din. Dynamic Torsional Rigidity
Cr Radial Rigidity
α Angular Misalignment. Kr Radial Misalignment. Ka Axial Misalignment
Elastic element
80 Shore A92 Shore A98 Shore A64 Shore D
Color
Blue Yellow Red
Green
Te [°C]
-50 + 80-40 + 90-30 + 90-30 + 100
Tmax [°C]
-60 + 120-50 + 120-40 + 120-40 + 140
S
Note
Observe safety laws regarding protecting personnel from rotating equipement.
Ringfeder Corporation
RINGFEDER Products are available from MARYLAND METRICSP.O. Box 261 Owings Mills, MD 21117 USA email: [email protected] web: http://mdmetric.com
The coupling must be chosen so that the applied working loads do not exceed the allowable values whatever the workingconditions.
1. Nominal torqueThe nominal coupling torque must be greater than or equal to the nominal torque of the drive machine for all workingtemperatures.
TKN ≥ Tk • S� • SD
2. Torque peak valuesThe maximum coupling torque must be greater than or equal to the torque peaks that occur during operation for all workingtemperatures.
3. Periodic torque inversionsBy means of resonanceWhen the resonance frequency is passed rapidly below the operational interval, just a few torque peaks are seen. The generat-ed alternating loads must be compared with the maximum torque that the coupling can support.
density kilogram per kg/m3 pound per kg/m3 16.018 16 kg/m3 = 1 lb/ft3
cubic meter cubic foot
mass gram g ounce g 28.35 28 g = 1 ozkilogram kg pound kg 0.4536 1 kg = 35 ozton t tons (US) t 0.90718 1 kg = 2.2 lbs
force Newton N ounce N 0.278 1 N = 3.6 ozpound N 4.448 4.4 N = 1 lb
1 kN = 225 lb
stress mega pascal MPa pound/sq in MPa 0.00689 1 MPa = 145 psior (Newton per (PSI) (N/mm2) 7 MPa = 1000 psi = 1 ksipressure square millimeter) N/mm2
torque Newton meter N-m inch ounce N-m 0.00706 1 N-m = 142 in ozinch pound 0.11298 1 N-m = 8.85 in-lbfoot pound 1.3558 1.356 N-m = 1 ft-lb
1 N-m = 0.74 ft-lb
energy Joule J foot pounds J 1.3558 1 J = 0.75 ft-lbor work calories 4.187 1 J = 4 calories
temperature degree celsius °C Fahrenheit °C 0.556 (°F-32) 0 °C = 32 °F (accurate)20 °C = 68 °F (accurate)
100 °C = 212 °F (accurate)
Conversion from US-customary units
Kind ofDimension
MetricUnit
Symbol ConvertedFrom: To: Factor
For Quick ReferenceApproximate Factor
1 Factor 0.0254 applies when 1 micro inch (µin) is listed like this: 1 µinExample: 120 µin = 120�0.0254 = 3.048 micrometers (µm)
Factor 25400 applies when 1 micro inch (µin) is listed like this: .000001 inExample: .00012 in = .00012�25400 = 3.048 micrometers (µm)
Equations
Torque (in.-lbs) = 63025 � HorsepowerRPM
Horsepower = T (in.-lbs.) � RPM63025
Torque (ft.-lbs) = (5252) (H.P.)RPM
Horsepower = (T) (ft.-lbs.) � RPM5252
11Ringfeder Corporation
RFC SPECIALTY PRODUCTS
In accordance with our established policy to constantly improve our products, the specifications contained herein are subject to change without notice.
Since our Engineers cannot be aware of all applications and cannot control all the factors that may affect the function of our products, our warranty applies toour products only.
TECHNICAL ASSISTANCECall us Toll Free at 1–800–638-1830
Please let us know what your specific requirements are andwe shall be very happy to work out detailed recommenda-tions without any obligation. Just send a sketch with yourrequirements and specifications.
Call or write for more information.Visit our website: www.mdmetric.com
Our Representative:
Trasco® ES
RING-flex® Single Flexing andDouble Flexing Couplings withRingfeder® Shrink Discs®
Assure a totally backlash-free connec-tion with precise synchronization capa-bility. Additional features: Clearance fitsfor hub/shaft connection allow easyassembly and free axial movementcompensation during installation whicheliminates unwanted pre-loading or pre-stressing of the flexible elements.
ARCUSAFLEX® FlywheelCouplingsHighly flexible, backlash-free, vulcanizedrubber disc couplings designed to cou-ple the flywheel of an internal combus-tion engine to the shaft of the drivenmachine. Rubber disc element acceptsrelatively high angular, axial and parallelmisalignments. Flange dimensionsaccording to SAE J620 standards.
Multi Mont OCTA FlywheelCouplingsTorsionally flexible, economical flangecouplings for connecting the flywheel ofa combustion engine to the input shaftof a driven machine. Rubber elementsdampen vibrations and accommodatemisalignments.
RFC Specialty Locking DevicesRingfeder Corporation excels at special-ty keyless shaft/hub connection solu-tions. From 1/4” shafts to 30” shafts,our engineers have the solution.
BALL DETENT TORQUE LIMITERS Type BDThese accurate ball/roller and sockettorque limiters are easily adjustable fordifferent torque settings. In the event ofan overload, personnel and equipmentare protected as these devices discon-nect mechanically and make contactwith a limit switch that sounds andalarm or otherwise shuts the drivedown. Available in various configura-tions and combinations with couplings.
FRICTION TORQUE LIMITERType FCEasily adjustable, these torque limitersrely on friction to transmit the set torque.When an overload occurs, these devicesslip until the overload is removed or themachine is reset. Available in variousconfigurations and combinations withcouplings.
RINGFEDER Products are available from MARYLAND METRICSP.O. Box 261 Owings Mills, MD 21117 USA email: [email protected] web: http://mdmetric.com