WHEN Newsletter - Q3 2014 Federal Safety Standards for Heavy Trucks - Part 1

WHEN — Q3 2014

8

Dayton Parts LLC (continued from page 7)

Brake Recovery – (continued) Here’s what a typical brake recovery graph looks like.

This part of the test tells us if the friction material can continue to create sufficient torque after it has been subjected to higher drum temperatures. The 20 psi minimum is really a mute point now that ABS is once again mandated (more about that in Part 2). One last side note here. While reading through how this test is conducted, the ability of the brake drum to dissipate heat in a sufficient manner becomes very obvious. You would not get the same results shown in the charts here with a “value” drum. In closing remember this test is only required for friction materials that are seeking OE approval. Aftermarket friction materials are not required to have this test done in order to be sold. Most aftermarket friction material manufacturers do have this test done on their own accord which is good. Never purchase any friction material where this test cannot be supplied. In the next edition we’ll pick up where we left off around 1980 and go to the present plus a look beyond.

Brake Recovery

Link Testing Laboratories, Inc.

120

1200

110

1100

Actual Wheel Load (lb) — 11451.7 2 Actual Inertia (slug/ft ) — 950 Brake Type — Meritor Drive Rolling Radius (in) — 19.6 Slack Adjuster — Haldex 5.5" Air Chamber — MGM 3030 Brake Drum — Webb 66864

100

1000

90

900

80

800

70

700

60

600

50

500

Air Pressure

40 Pressure (psi)

400

DrumTemperature

30

300

Initial Lining Temp (Deg °F)

20

200

Dayton Parts DP23 Friction Material

10

100

0

0

As always I hope you found this edition of WHEN informative.

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4

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8

10

12

14

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18

20

Recovery Stops

Regards,

Steven S. Wolf Axle Group Product Manager Dayton Parts, LLC

Look for the Part 2 continuation of this edition of WHEN in the Q4 Dayton Parts Distributor Mailing

Dayton Parts, LLC • PO Box 5795 • Harrisburg, PA 17110-0795 • 800-233-0899 • Fax 800-225-2159 Visit us on the World Wide Web at www.daytonparts.com DP/Batco Canada • 12390 184th Ave. • Edmonton, Alberta T5V 0A5 • 800-661-9861 • Fax 888-207-9064