ELEMENT TYPES
Hammer Head Two stage with up to 9 degrees of deflection. More torsionally flexible than the loop type, usually has smaller diameter element than our other designs but still retains the ability to be mounted either way round on the flywheel and rotate in either direction.
Loop Type Linear stiffness up to 3 degrees of deflection. General purpose robust element which can be mounted either way round on the flywheel and can rotate in either direction.
High Deflection (H/D) A maximum deflection up to 30 degrees, slightly larger diameter element than other designs and can easily be fitted to rotate in the standard direction of rotation (counter- clockwise looking at the flywheel). With the element facing the gearbox. Suitable for work boats with slow speed work and pleasure boats.
FAIL SAFE DESIGN If the flexible element fails, the rivets on the spline plate will engage the rivets on the backing plate. This will allow the drive to be maintained in the unlikely event of an element failure.
Spline Plate Rivet
Backing Plate Rivet
Element
DAMPER PLATE SELECTION PROCEDURE The R&D Marine Damper Plate is comprised of 3 main components, Spline Plate, Element, and Back Plate. These 3 components are given a code which make up the finished part number. The following procedure will lead you through the selection process. 1. SELECT ELEMENT Select the correct power and style of element for the application. Use the manufacturer’s maximum torque figure for the engine or calculate from the known data of maximum horsepower rating and RPM. Using the example installation we get 61.25 ft. lbs. of torque. Example
To calculate output torque of engine: Formula:
1. Westerbeke 42B with 42HP at 3,600 RPM 2. ZF HBW35 transmission with 10 tooth spline 3. Back plate diameter 6.12", fixing holes 5" x 0.25" on 5.593"
Max Horsepower of Engine Engine Speed (Max RPM)
X 5,250 = Torque lbft
Example: x 5,250 = 61.25 ft. lbs.
42 3,600
From the Element Selection Chart (List #1) we see the most suitable element has a code of AM and a fixing of 3 x 3/8 (4.00).
2. SELECT SPLINE / SPLINE CODE Select the correct spline/ spline code (List #2) to suit the gearbox input shaft. Using the example, go to the gearbox details to find the ZF-Hurth HBW 35 has a 10 Tooth DIN 5464 input spline. Next, use List #3 to choose the spline code that corresponds with the chosen element ("AM"). In this case we choose spline code "22" because it is compatible with the "AM" element. 3. SELECT BACKING PLATE Select the correct back plate to suit the flywheel. Using the example, go to List #4 to find the matching bolt pattern to fit the flywheel fixing, in this case back plate code "4". Damper required for this example: Spline Plate: 22 | Element: AM | Back Plate: 4 | Part number: RD-22-AM-4
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