OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

March, 3 1998

David A. Miller
Director of Product Assurance
Blount Incorporated
535 Mack Todd Road
Zebulon, North Carolina 27597

Dear Mr. Miller:

This is a response to your letter of January 16, 1998 requesting an interpretation from the Occupational Safety and Health Administration's (OSHA) Logging Standard, 29 CFR 1910.266. As a manufacturer of forest harvesting equipment, you asked for an interpretation of five specific questions (listed below) from our logging standard 29 CFR 1910.266(f)(7), Brakes.

Question #1

Must there be three separate independent brake systems?


29 CFR 1910.266 (f)(7)(H) states that each machine shall be equipped with a secondary braking system, such as an emergency brake or a parking brake, which shall be effective in stopping the machine and maintaining parking performance, regardless of the direction of travel or whether the engine is running. Therefore, only two separate independent brake systems are required on machines.

Question #2

Can there be a sharing of (common) brake components between three brake systems and to what extent?


No, common brake components cannot be shared between three brake systems. Each machine must have an independent braking system for the service brake, and an independent brake or parking brake. This redundant braking system cannot be shared because in an emergency, the operator may need to activate both braking systems at one time, and if the braking components are shared there would be only one braking system.

Question #3

Can the parking brake (or parts of it) be considered a backup or secondary system?


Yes, the parking brake or parking brake (separate from the service brake) can be considered a backup or secondary system.

Question #4

If a machine has an independent hydraulic drive to each of its two drive wheels can the hydrostatic braking applied separately and independently to each wheel be considered as two separate brake systems?


No, if a machine has a separate and independent hydraulic drive for each of its two drive wheels, it is considered one braking system.

Question #5

If a brake system is hydraulically applied, utilizing an engine driven pump as its pressure supply, and has an hydraulic accumulator for brake pressure supply when the engine is not running, how many applications of the brakes does the accumulator have to provide after the engine is stopped?


If the brake system is hydraulically applied, and has an hydraulic accumulator for brake pressure supply when the engine is stopped, the accumulator must provide for only one application of the brakes.

If you have any questions or concerns, please feel free to contact Russelle McCollough of my staff, at (202) 219-8031.


John B. Miles, Jr., Director
Directorate of Compliance Programs