In the hydraulic system of a concrete pump truck, the outrigger and arm system have certain particularities. For safety reasons, each vertical outrigger cylinder and each boom cylinder are equipped with a balance valve (commonly known as "hydraulic lock"). Only when the reversing valve is opened will the balance valve connect to the oil circuit. Otherwise, the balance valve remains closed, isolating the hydraulic oil inside and outside the cylinder.
Then, when extending the legs and boom in the later stage of preheating, if you want to squeeze all the original low-temperature hydraulic oil in the cylinder back into the tank, maintain the temperature balance of the hydraulic oil in the cylinder, and avoid the cylinder from spontaneously occurring due to the temperature difference on both sides of the cylinder piston. , the cylinder must be allowed to move a full stroke from fully retracted to fully extended, otherwise some hydraulic oil will not be able to return to the tank. This full-stroke operation is a waste of time and diesel. What's more, if the stretching space is limited, the full stroke is simply impossible.
Therefore, before we officially extend the outriggers and booms, we should use multiple reciprocating movements to expand and contract each oil cylinder multiple times within a small range to fully mix the original low-temperature oil in the cylinder with the high-temperature oil entering the cylinder. , using the principles of convection and conduction to increase the overall temperature of the hydraulic oil in the cylinder. After the oil temperature in the cylinder is balanced, formally support the legs and unfold the boom.
We hope that all operators of concrete pumping equipment will develop good habits of regular operations in their daily work and successfully complete construction tasks!