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Air and endurance brake systems
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
Other more elaborate versions of relay valve may be used for certain applications. One example is the inverse relay valve that was once used with tractive unit and trailer combinations with a single-line connection. It was so arranged that air passed through it to the trailer reservoir and when storage pressure fell with brake application it triggered the relay valve, thereby admitting air to the trailer brakes from their nearby reservoir. This system had the disadvantage that no air could be supplied to the trailer reservoir during prolonged periods of downhill braking. Another example is the relay emergency valve, which is associated with modern tractive unit and trailer combinations. Apart from speeding up the application and release of the trailer brakes, it also has an emergency valve that allows automatic application of the trailer brakes should either the air pressure in the feed or emergency line to the trailer reservoir fall too low, or in the event of the trailer breaking loose from the tractive unit. For this reason it is known to American engineers as a breakaway valve.
An investigation towards intelligent tyres using finite element analysis
Published in International Journal of Pavement Engineering, 2020
Pooya Behroozinia, Seyedmeysam Khaleghian, Saied Taheri, Reza Mirzaeifar
The tyre normal load was controlled using an air spring and a pneumatic pressure transducer, the schematic of normal load control mechanism is shown in Figure 7(a). The maximum load capacity for the normal load controller system (considering the weight of the trailer and air spring and transducer loading capacity) is 10,000 pounds. Also, the wheel slip angle was controlled using a Parker servo motor – motor control system which is shown in Figure 7(b).