| 摘要 |
The preheating of hydraulic systems is prior art. It is generally done by operating the system without load until the prescribed minimum temperature is attained. However, in the known types of preheating circuits the operating elements (hydraulic cylinders) are not included. The invention relates to an arrangement in which the operating elements are included in the heating circuit.Appropriate circuits are provided for the various operating states of the hydraulic cylinder, i.e. "neutral", "retract piston rod" and "extend piston rod". The provision of an additional passageway in the piston rod through which the hydraulic oil can pass into the hydraulic cylinder is an essential feature by means of which the oil can circulate without the application of pressure while the system is in the neutral operating state. By using the invention, it is possible to preheat hydraulic circuits in the neutral, non-operating state, thusavoiding damage to the operating elements, increasing the lifetime of the wear parts and guaranteeing reliable operation of the hydraulic system. The inventionis suitable in particular for use in conveyor systems operating in cold regions.
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