Trans 308.01(1)(1) Every truck or truck tractor equipped with air brakes, when used for towing other vehicles equipped with air brakes, shall be equipped with 2 means of activating the emergency features of the trailer brakes. One of these means shall operate automatically in the event of reduction of the towing vehicle air supply to a fixed pressure which shall not be lower than 20 pounds per square inch nor higher than 45 pounds per square inch. The other means shall be a manually controlled device readily operable by a person seated in the driving seat. Its emergency position or method of operation shall be clearly indicated. In no instance may the manual means be so arranged as to permit its use to prevent operation of the automatic means. The automatic and manual means required by this section may be, but are not required to be separate.

Trans 308.01(2)(2) Every truck tractor and truck when used for towing other vehicles equipped with vacuum brakes, shall have, in addition to the single control required by s. Trans 308.06 to operate all brakes of the combination, a second manual control device which can be used to operate the brakes on the towed vehicles in emergencies. Such second control shall be independent of other controls, unless the braking system be so arranged that failure of the pressure on which the second control depends will cause the towed vehicle brakes to be applied automatically. The second control is not required by this rule to provide modulated or graduated braking.

Trans 308.01(3)(3) Air brake systems installed on towed vehicles shall be so designed, by the use of “no-bleed-back” relay emergency valves or equivalent devices, that the supply reservoir used to provide air for brakes shall be safeguarded against backflow of air to the towing vehicle upon reduction of the towing vehicle air pressure.

Trans 308.01(4)(4) The requirements of subs. (2) and (3) shall not be applicable to motor vehicles in driveaway-towaway operations.

Trans 308.02(1)(1) Designed and constructed of proper material and so installed and maintained as to insure proper continued functioning;

Trans 308.02(2)(2) Sufficiently long and flexible as to accommodate without damage all normal motions of the parts to which they are attached;

Trans 308.02(3)(3) Suitably secured against chafing, kinking, or other mechanical injury; and

Trans 308.02(4)(a)(a) Brake hose shall be so constructed as to insure adequate and reliable functioning and shall conform to the appropriate specification set forth in the SAE Standards for “Hydraulic Brake Hose Assemblies for use with Non-Petroleum Base Hydraulic Fluids,” SAE J1401a; “Automotive Air Brake Hose and Hose Assemblies,” J1402c; or “Vacuum Brake Hose,” J1403a. (See 1980 SAE Handbook.)

Trans 308.02(4)(b)(b) The above referred to SAE Standards are on file in the offices of the department of transportation, the secretary of state and the legislative reference bureau, and may be obtained from the Society of Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, Pennsylvania 15096.

Trans 308.02 HistoryHistory: Cr. Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.02 and am. (4), Register, September, 1980, No. 297, eff. 10-1-80; correction in (4) (b) made under s. 13.92 (4) (b) 6., Stats., Register March 2012 No. 675.

Trans 308.03(1)(1) Be adequate in material and construction to insure proper continued functioning;

Trans 308.03(2)(2) Be designed, constructed, installed and maintained so as to insure, when properly connected, an attachment free of leaks, constrictions, or other defects;

Trans 308.03(3)(3) Have suitable provision in every detachable connection to afford reasonable assurance against accidental disconnection;

Trans 308.03(4)(4) Have the vacuum brake engine manifold connection at least three-eighths inch in diameter.

Trans 308.04Trans 308.04 Brake lining. The brake lining on every trailer type vehicle shall be so constructed, installed and maintained as not to be subject to excessive fading and grabbing and shall be adequate in thickness, means of attachment, and physical characteristics to provide for safe and reliable stopping of the vehicle.

Trans 308.05Trans 308.05 Brakes to be operative. All brakes with which trailer-type vehicles are equipped shall be operative at all times except brakes need not be operative on disabled vehicles being towed.

Trans 308.06Trans 308.06 Single valve to operate all brakes. Every motor vehicle, the date of manufacture of which is subsequent to June 30, 1953, which is equipped with power brakes, shall have the braking system so arranged that one application valve shall when applied operate all the service brakes on the motor vehicle or combination of motor vehicles. This requirement shall not be construed to prohibit motor vehicles from being equipped with an additional valve to be used to operate the brakes of a trailer or trailers. This section shall not be applicable to driveaway-towaway operations unless the brakes on such operations are designed to be operated by a single valve.

Trans 308.07(1)(1) Air brakes as provided in sub. (4). Every truck and truck tractor using compressed air for the operation of its own brakes or the brakes of any towed vehicle shall be equipped with a warning signal readily audible or visible to the driver, which will give continuous warning at all pressures below a fixed pressure not less than one-half of the compressor governor cut-out pressure. In addition, each such vehicle shall be equipped with a pressure gauge which will indicate to the driver the pressure in pounds per square inch available for braking.