[Code of Federal Regulations]
[Title 40, Volume 18]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR91.306]

[Page 319]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 91--CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES--Table of 
Contents
 
              Subpart D--Emission Test Equipment Provisions
 
Sec. 91.306  Dynamometer torque cell calibration.

    (a)(1) Any lever arm used to convert a weight or a force through a 
distance into a torque must be used in a horizontal position for 
horizontal shaft dynamometers ( five degrees). For vertical 
shaft dynamometers, a pulley system may be used to convert the 
dynamometer's horizontal loading into the vertical plane.
    (2) Calculate the indicated torque (IT) for each calibration weight 
to be used by:

IT=Moment Arm (meters)xCalibration Weight (Newtons)

    (3) Attach each calibration weight specified in Sec. 91.305(b)(2) to 
the moment arm at the calibration distance determined in paragraph 
(a)(2) of this section. Record the power measurement equipment response 
(N-m) to each weight.
    (4) Compare the torque value measured to the calculated torque.
    (5) The measured torque must be within two percent of the calculated 
torque.
    (6) If the measured torque is not within two percent of the 
calculated torque, adjust or repair the system. Repeat steps in 
paragraphs (a)(1) through (a)(6) of this section with the adjusted or 
repaired system.
    (b) Option. A master load-cell or transfer standard may be used to 
verify the torque measurement system.
    (1) The master load-cell and read out system must be calibrated with 
weights specified in Sec. 91.305(b)(2).
    (2) Attach the master load-cell and loading system.
    (3) Load the dynamometer to a minimum of three equally spaced torque 
values as indicated by the master load-cell for each in-use range used.
    (4) The in-use torque measurement must be within two percent of the 
torque measured by the master system for each load used.
    (5) If the in-use torque is not within two percent of the master 
torque, adjust or repair the system. Repeat steps in paragraphs (b)(2) 
through (b)(4) of this section with the adjusted or repaired system.
    (c) Calibrated resistors may not be used for dynamometer torque 
transducer calibration, but may be used to span the transducer prior to 
engine testing.
    (d) Other engine dynamometer system calibrations such as speed are 
performed as specified by the dynamometer manufacturer or as dictated by 
good engineering practice.