China
Africa
Explore chapters and articles related to this topic
Suspension systems
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
For modern heavy vehicles the use of variable-mass air suspension on their tractive units (Figure 23.46) and semi-trailers (Figure 23.50) brings advantages in respect of smoother riding that reduces driver fatigue and better protects fragile cargo, provides height control for ease of trailer coupling and docking, eases maintenance requirements, and causes less damage to the road. In the case of buses the use of air suspension, apart from improving ride comfort, allows a constant height to be maintained for the entrance platform or step, which has always been an important consideration as far as passenger safety is concerned.
VTT – a virtual test truck for modern simulation tasks
Published in Vehicle System Dynamics, 2021
Georg Rill, Florian Bauer, Mathias Kirchbeck
The axles of commercial on-road trucks are often suspended by air springs. Besides a ride-cushioning effect an air suspension provides a level control that maintains the steady-state ride height regardless of load. The air springs of two or three rear axles are usually coupled to provide a waking-beam like performance of the axle combination. Figure 5 shows two air springs that are coupled by a pipe.Each air spring is characterised by the polytropic exponent κ, the effective cross-section area , the excessive pressure in design position , an the volume in design position. The polytropic state change delivers The time derivative of the transfer volume is given by where denotes the cross-section of the connecting pipe and is the velocity of the air flow. According to Bernoulli the flow dynamics is defined by where is assumed, λ denotes the pipe friction factor, ℓ and d describe the length and the diameter of the connecting pipe, ξ is a pressure loss factor, and represents the laminar pressure loss at the reference flow velocity . For the sake of simplicity is set in this approach. Combining (4) with (5) finally delivers a first-order differential equation for the transfer volume where collects all turbulent losses.