Front end loader vehicles are prone to excessive pitching when travelling at high speed, partly due to the absence of axle suspension. This paper studies the fundamental design of a hydropneumatic suspension for a medium wheel loader. The vehicle is analysed using an analytical frequency response model as well as multibody simulations. Results show that favourable pitching response can be achieved by increasing the rear axle stiffness, but also that a similar effect is achieved with higher front axle stiffness. For the loaded vehicle, it is also found that the benefits of an optimal stiffness distribution are offset to some extent by the reduction in relative damping as the vehicle mass and inertia increases. Thus, it is desirable to increase suspension damping under load to maintain a suitable level of relative damping. The objective of this paper is to investigate how accepted design practices and theoretical methods that have been developed by the car industry can be put to use in the suspension design for an engineering vehicle. The vehicle studied is a wheel loader in the 20-ton range. Results indicate that desirable pitch response is achieved using either a stiffer or a weaker rear axle, in contrast to the traditional passenger car design rules stating that a stiffer rear axle is universally optimal for pitch attenuation. Furthermore, it is seen that vertical accelerations are amplified when pitching motion is reduced, although the penalty is quite small, indicating that substantial pitch reduction can be achieved for the loader at a relatively small cost in vertical acceleration. The results from analytical calculations and multibody simulations are generally in agreement with regards to the effects of suspension stiffness setup. The analytical model seems to show more beneficial results for the reverse Olley configuration than what can be seen in multibody simulations.
Pitch comfort optimisation of a front end loader using a hydropneumatic suspension
2007
9 Seiten, 15 Bilder, 3 Tabellen, 9 Quellen
Conference paper
English
Pitch Comfort Optimisation of a Front End Loader using a Hydropneumatic Suspension
SAE Technical Papers | 2007
|2007-01-4269 Pitch Comfort Optimisation of a Front End Loader using a Hydropneumatic Suspension
British Library Conference Proceedings | 2007
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