e-CFR Navigation Aids


Simple Search

Advanced Search

 — Boolean

 — Proximity


Search History

Search Tips


Latest Updates

User Info


Agency List

Incorporation By Reference

eCFR logo

Related Resources

Electronic Code of Federal Regulations

We invite you to try out our new beta eCFR site at https://ecfr.federalregister.gov. We have made big changes to make the eCFR easier to use. Be sure to leave feedback using the Feedback button on the bottom right of each page!

e-CFR data is current as of January 15, 2021

Title 40Chapter ISubchapter UPart 1066Subpart C → §1066.245

Title 40: Protection of Environment
Subpart C—Dynamometer Specifications

§1066.245   Response time verification.

(a) Overview. This section describes how to verify the dynamometer's response time to a step change in tractive force.

(b) Scope and frequency. Perform this verification upon initial installation, within 370 days before testing (i.e., annually), and after major maintenance.

(c) Procedure. Use the dynamometer's automated process to verify response time. You may perform this test either at two different inertia settings corresponding approximately to the minimum and maximum vehicle weights you expect to test or using base inertia and two acceleration rates that cover the range of acceleration rates experienced during testing (such as 0.5 and 8 (mi/hr)/s). Use good engineering judgment to select road-load coefficients representing vehicles of the appropriate weight. Determine the dynamometer's settling response time, ts, based on the point at which there are no measured results more than 10% above or below the final equilibrium value, as illustrated in Figure 1 of this section. The observed settling response time must be less than 100 milliseconds for each inertia setting. Figure 1 follows:

eCFR graphic er28ap14.066.gif

View or download PDF

[79 FR 23823, Apr. 28, 2014, as amended at 81 FR 74199, Oct. 25, 2016]

Need assistance?