Poona Couplings

Flexible Couplings ( DCB ) - Coupling Manufacturer

 
Flexible Couplings ( RB )
Flexible Couplings ( RB )
 
 
 
Flexible Couplings ( RB )
Fail safe coupling for use on reciprocating machinery up to 5520 KNm. Torque up to 849.5 KNm.
1200 mm Ø & 9.5 inch Rubber Block
 
THE STANDARD RANGE COMPRISES
* Flywheel to shaft
* Flywheel to flange
* Shaft to shaft
 
APPLICATIONS
* Marine propulsion
* High power generator sets & Reciprocating compressors
 
FEATURES BENEFITS
* Intrinsically fail safe
* Ensuring continuous operation of the driveline in the unlikely event of rubber damage.
* Control of resonant torsional vibration
* Achieving low vibratory loads in the driveline components by selection of optimum stiffness characteristics
* Severe shock load protection
* Avoiding failure of the driveline under short circuit and other transient conditions.
* Maintenance free
* With no lubrication or adjustment required resulting in low running cost
* Misalignment capability
* Allows axial and radial misalignment between the driving and driven machines.
* Noise attenuation
* Giving quiet running condition in sensitive applications by the elimination of metal to metal contact.
 
CONSTRUCTIONAL DETAILS

* Available options are : Series6, Series8, Series 10, series 16,
* 1,2,3,4 or 5 rubber elements per cavity are available. Rubber elements upto 15" diameter are manufactured.
* The inner and outer members are manufactured in steel to BS3100 Grade A1.
* Some sizes are avaialble in S.G. IRON Castings to BS2789 Grade 420 / 12.
Flexible Couplings
 
DCB Typical Application
DCB Series 6
Flexible Couplings (DCB Series 6)
DCB Series 6
Flexible Couplings (DCB Series 6)
DCB Series 8
Flexible Couplings (DCB Series 8)
DCB Series 8
Flexible Couplings (DCB Series 8)
DCB Series 8
Flexible Couplings (DCB Series 8)
 
 
 
DCB - GS 624.5 ASSEMBLY DRAWING DCB 839.5 SP ASSEMBLY
   
DCB 846.6 ASSEMBLY DCB 849.5 ASSEMBLY
   
DCB TECHNICAL DATA

1.1 Torque Capacity-- Diesel Engine Drives

The DCB Coupling is selected on the " Nominal Torque, Tkn " without service factors.
The full torque capacity of the coupling for transient vibration whilst passing through major criticals on run up is published as the Maxium Torque, Tkmax
( Tkmax = 3 X Tkn )

There is additional torque capacity built within the coupling for short circuit torques.
The published " Vibratory torque, TKw ", relates to the amplitude of the permissible continuous torque fluctuation.The vibratory torque values shown in the "Technical Data are at a frequency of 10 Hz. The measure of acceptability of the coupling for vibrating drives is published as " Allowable dissipated Heat at Ambient Temperature 30o C. "

1.2 TRANSIET TORQUE--
Prediction of transient torques in marine driven can be complex. Normal installations are well provided for by selecting couplings based on the " Nominal torque Tkn " Transients, such as start up and clutch manoeuvre, are usually within the " Maximum Torque, Tkmax " for the coupling.
Care needs to be taken in the design of couplings with shaft brakes, to ensure coupling torques are not increased by severe deceleration.
Sudden torque application of propulsion, such as thrusters or waterjets, need to be considered when designing the coupling connection.

2.0 STIFFNESS PROPERTIES
The Poona Couplings remains fully flexible under all torque conditions. The DCB series is a non-bonded type operating with the Rubber-in-Compression principle.

2.1 AXIAL STIFFNESS
When subject to axial misalignment, the coupling will have an axial resistance which gradually reduces due to the effect of vibratory torque.
The axial stiffness of the coupling is torque dependent. The variation is as shown in the Technical Data on pages 16 to 22

2.2 RADIAL STIFFNESS

The radial stiffness of the coupling is torque dependent, and is as shown in Technical Data on pages 16 to 22.

2.3 TORSIONAL STIFFNESS

The torsional stiffness of the coupling is dependent upon applied torque and temperature as shown in the Technical Data on pages 16 to 22.

2.4 PREDITION OF THE SYSTEM TORSIONAL VIBRATION CHARACTERISTICS
2.4.1 Use the torsional stiffness, as published in the catalogue, which is based upon data measured at 30 C ambient temperature.
2.4.2 Repeat the calculation made in 2.4.1 but using the maximum temperature connction factor St100 and dynamic magnifier connection factor M100 for the selected rubber. Use tableson page 15 to adjust values for both torsional stiffness and dynamic magnifier i.e. Ct100 = Ctdyn x St100

2.4.3-- Review calculations
2.4.1 and 2.4.2 and if the speed range is clear of critical which do not exceed the allowable heat dissipation value as published in the catalogue then the coupling is considered suitable for the application, with respect to the torsional vibration characteristics. If there is a critical in the speed range , then the actual temperature of the coupling should be calculated at this speed.

 
 

2.5 PREDITION OF THE ACTUAL COUPLING TEMPERATURE AND TORSIONAL STIFFNESS

2.5.1 Use the torsional stiffness as published in the catalogue. This is based upon data measured at 30 C
( M30 )
2.5.2 Compare the synthesis value of the calculated heat load in the coupling ( Pk )in the speed of interest, to the " Allowable Heat Dissipation " ( Pkw )
The coupling temperature rise

2.5.3 Calculate the temperature corrector factor St, from 2.6 ( If coupling temperature >100 C, then use St100. Calculate the dynamic Magnifier as per 2.7. Repeat the calculation with new value of coupling stiffness and dynamic magnifier.

2.5.4 Calculate the coupling temperature as per 2.5. Repeat calculate until the coupling temperature agrees with the correction factors for torsional stiffness and dynamic used in the calculation.

2.6 Temperature Correction Factor
 
 
2.7 DYNAMIC MAGNIFIER CORRECTION FACTOR
The dynamic Magnifier of the rubber is subject to temperature variation in the same way as the torsional stiffness
 
 

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