Document ID: chunk:federal_register_of_legislation:F2021C00434:body:0:p9
Version: federal_register_of_legislation:F2021C00434
Segment Type: other
Provision Reference: 
Character Range: 25399–28453

employing two or more independent circuits, the energy requirements for retaining the secondary brakes in the released position must be supplied from the 'Stored Energy' device(s) of the other circuits or optionally from an independent 'Stored Energy' device; and
4.5.6.3.                                      with the 'Stored Energy' device charged to its 'Average Operating Pressure' it must have sufficient capacity to permit the 'Secondary Brake System' to be applied and released not fewer than:
         4.5.6.3.1.  Two (2) times when the brakes are adjusted so that the distance travelled by the device which directly actuates the brake shoe or pad is a maximum, or
         4.5.6.3.2.  Three (3) times when the brakes are adjusted to the 'Manufacturer' specifications.
4.5.7.                                            In a vehicle equipped with a 'Brake Power Assist Unit' normally supplied with high pressure fluid by an engine driven pump, a back-up system must be regarded as a 'Secondary Brake System' if the back up source of power assistance is immediately energized by a pump driven independently of the vehicle engine.
4.5.8.                                            Every motor vehicle equipped to tow a trailer must be so equipped that its brake system remains operative and has the performance of the Laden Secondary Brake Test (item 7 of Table 1) in the event of the trailer becoming disconnected. This protection must be automatic.
4.5.8.1.                        Protection systems may vent the trailer 'Supply Line 35/...' but this must not commence;
4.5.8.2.1.                  until the energy level in the 'Supply Line 35/...' falls below 0.54 'E' (350 kPa) or,
4.5.8.2.2.                  if the 'Supply Line 35/...' energy level is reducing at a rate of not less than 0.15E/sec (100 kPa/sec), until the energy level in the 'Supply Line 35/...' falls below 0.65 'E'(420 kPa).
4.5.9.                                            Every motor vehicle which provides its 'Secondary Braking System' by means of a 'Split Service Brake System' and which is equipped to tow a trailer which uses air at positive pressure, must be so equipped that the operation of the 'Secondary Brake System' causes a control signal proportional to the degree of braking to be present in the 'Control Line 35/...'.
4.5.10.                                        An additional 'Control' may be fitted to provide for the independent application of a trailer 'Parking Brake System 38/00'.   Operation of the 'Control' must cause the pressure in the 'Supply Line 35/...' to drop below 35 kPa and remain below 35 kPa independently of the motor vehicle's 'Service Brake System'.
4.5.10.1.                    The 'Control' which actuates this function must be located so that it is readily accessible to the driver in the normal driving position and, marked with the words 'TRAILER EMERGENCY  BRAKES' and a description of how to operate the control, e.g. 'TRAILER EMERGENCY BRAKES – PULL'.  The 'Control' must also be marked with the words 'NOT FOR PARKING'.