Technical Handbook
Rev. 1.6
WWW.ROTREX.COM
Page 11 of 41
Designing and handling interfaces
4. Designing and handling interfaces
4.1 Pulleys and other drive types
Rotrex provides 8 and 10 ribbed PK-type pulleys ranging from Ø70 to Ø110mm in diameter
in steps of 5mm (i.e., Ø70, Ø75, Ø80...). Check the technical datasheets for available
pulley sizes for specific superchargers. Rotrex highly recommends using standard Rotrex
pulleys. If you for some reason need to use a different design, please follow the technical
information and specifications on pulley design in Section 6.1 and 6.2. This will ensure a
proper coupling and a healthy bearing arrangement.
Not following these specifications
voids warranty and may result in permanent damage of the supercharger system and/or
other systems in the vehicle/application.
Repeatedly turning the input shaft on a new unit in the wrong direction (see supercharger
selection table, page 9) will result in detachment of the internal thread connection resulting
in supercharger damage.
Never use an impact wrench when mounting or changing pulleys.
Section 6.3 of this
document explains the procedure for assembling and disassembling pulleys.
The supercharger must be delivered with the pulley/pulley adapter pre-assembled to the
installer or end user to avoid claims arising from incorrect pulley assembly.
In case of any questions or doubt don’t hesitate to contact your supplier or Rotrex.
Use the formula in the box below to calculate the pulley size for a given application. The
target impeller rpm,
RPM
i
, should be found using a flow map and target values for pressure
ratio and air flow.
Do not exceed the maximum allowed supercharger speed.
𝑅𝑃𝑀 =
𝑅𝑃𝑀
,
× Ø𝑃𝑢𝑙𝑙𝑒𝑦 × 𝑅𝑎𝑡𝑖𝑜
Ø𝑃𝑢𝑙𝑙𝑒𝑦
or reorganized for pulley diameter...
Ø𝑃𝑢𝑙𝑙𝑒𝑦 =
𝑅𝑃𝑀
,
× Ø𝑃𝑢𝑙𝑙𝑒𝑦 × 𝑅𝑎𝑡𝑖𝑜
𝑅𝑃𝑀
where subscripts
i,e,s
denote impeller, engine
and supercharger.
Example:
Engine max speed: 7200rpm
Supercharger: C15-60
Impeller speed: 142krpm
Ratio of C15: 12.67:1
Crank pulley: 123mm
7200 × 12.67 × 123
142000
= 79
By rounding up we get the appropriate
pulley diameter to be 80mm
Note:
C15 drive ratio:
1:12.67
C30 drive ratio:
1:9.49
C38 drive ratio:
1:7.50
C38R drive ratio:
1:6
Pulley size
calculation
Содержание C15-16
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