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Testing Indicates CTD IDP Performance is Equivalent to Decoupler Pulleys and Superior to Clutch and Solid Pulleys in Isolating the Drive Belt from Engine Speed Fluctuations.
Comparison of Belt Tensioner Calming Effect by Alternator Pulley Type
Figure 1– Data shows that CTD and Litens IDP pulleys o er equivalent tensioner calming e ects. Solid pulleys pass on all the engine pulsations to the tensioner, stressing the FEAD system. Clutch pulleys lock and release suddenly, hammering the tensioner much like a solid pulley.
Comparison of Tensioner Motion under Load by Pulley Type
Figure 2– Data shows that CTD and Litens IDP pulleys are comparably e ective in decoupling the rotor from the belt. Solid and clutch pulleys expose the tensioner and belt-path components to increasing vibration, belt stretching, and radial loads as the alternator output increases.
Comparison of Engine Start Conditions by Pulley Type
Figure 3– Data shows that a solid pulley on this vehicle triggers large amplitude acceleration disturbances on the belt and tensioner during engine starts. Both CTD and Litens pulleys o er enough overrun to function equally in the amount belt calming e ect they add during engine starts as well as during sudden engine speed changes.
CTD and Litens Pulleys Functionally Equivalent
The data in gures 1–3 is from testing the dynamics of solid and IDP pulleys on 2003, 3.8L Chrysler van test engines with 160A alternators. This drivetrain was chosen since it’s the most common application equipped with OEM decoupler pulleys.
The data is consistent in showing that solid and clutch pulleys do not isolate the drive belt from engine speed pulsations as e ectively as Litens and CTD IDP decoupler pulleys. In all tests, Litens and CTD decoupling technologies show functionally equivalent performance.
Pulley Comparison Video
The strobe e ect freezes the pulley/rotor shaft and captures the spring responsive isolation of Litens and CTD IDP™ pulleys.
Note how the clutch pulley locks and overruns 3x per engine revolution, hammering the belt and causing tensioner vibrations.
Ongoing Durability Evaluation and Monitoring of CTD IDP Pulleys Shows No Failures and No Degradation in Performance Over Time. Figure
Figure 4– Internal springs from a CTD pulley used in service on a 2004 3.8L Chrysler van eet taxi. This photo shows discoloration but no signi cant physical degradation of the six high-temperature and chemical-resistant polymer springs after 100,000 miles of service. For comparison, new polymer springs are shown on the left.
Performance of CTD Pulley at 100,000 Miles Versus New Pulleys
Figure 5– After 100,000 miles CTD pulleys showed no signi cant degradation in performance and remain functionally equivalent to both new Litens IDP and CTD IDP pulleys.
Performance of CTD Pulley– 100,000 Miles Versus New
Figure 6– After 100,000 miles CTD pulleys showed no signi cant degradation in performance and remain functionally equivalent to a new pulleys.
Dynamics and Function of CTD Pulleys Evaluated During Taxi Fleet Trials
Figure 7– At 30 day intervals, CTD pulleys tted to test taxis were bench tested and evaluated. All CTD pulleys maintained performance standards and had no failures.
Continuing Long-term Field Use Test Status
Mileage as of February 2011 for the six highest mileage pulleys of the fourteen pulleys currently in use (all fourteen pulleys have accumulated over 30,000 miles thus far with no performance degradation). The mean time between failures (MTBF) for the OE pulley under similar field use test conditions is estimated to be 56,000 miles.