Hydraulic cylinders, hydraulic circuits and fire trucks

Abstract

The invention relates to the field of hydraulic pressure, and discloses a hydraulic cylinder, a hydraulic loop and a fire engine. The hydraulic cylinder comprises a cylinder body inner cavity, a first piston rod (11) for reciprocating acting on the cylinder body inner cavity, and a second piston rod (12), wherein the first piston rod (11) includes a first piston (111) and a first rod (112) connected together; a cavity (113) communicated with the cylinder body inner cavity is formed in the first rod (112); and the second piston rod (12) includes a second rod (121) fixedly connected with the cylinder body inner cavity, and a second piston (122) connected with the second rod (121). The second rod (121) extends to penetrate through the first piston (111) to enter the cavity (113); and the second piston (122) is acted on the cavity wall of the cavity (113) during moving of the first piston (111). The hydraulic cylinder can effectively prevent self wrong actions so as to effectively prevent wrong swing actions of a working bucket of the fire engine.

Description

technical field [0001] The invention relates to the hydraulic field, in particular to a hydraulic cylinder, a hydraulic circuit and a fire engine. Background technique [0002] At present, more and more fires occur in high places, such as high-rise buildings, so the use of climbing platform fire trucks is becoming more and more extensive. Ascending platform fire trucks are used to assist firefighters in completing fire fighting in high-rise buildings, tall facilities, oil tanks, etc., rescuing trapped people, rescuing valuable materials and completing other rescue tasks. Generally, a working bucket is arranged on the climbing platform fire truck, and the working bucket is controlled through a hydraulic circuit to assist firefighters in carrying out fire fighting or rescue operations. For the convenience of rescue, the working bucket needs to be able to swing left and right, so that it can better approach the burning building, so that the rescue work can be carried out bette...

AI Technical Summary

Problems solved by technology

[0003] However, in the hydraulic circuit of the working bucket on the existing climbing platform fire truck, due to the existence of system back pressure and the leakage of the neutral position of the reversing valve, it may cause the malfunction of the working bucket swing, which may cause the vehicle to in an uncontrollable state

like image 3 As shown, since the swing of the working bucket only needs to overcome the friction force of the bearing, only a small pressure is required. Therefore, a check valve 4' is usually installed in the existing hydraulic circuit. When the three-position reversing valve 3 is in the neutral position, the oil cylinder 1' should be locked, but there is leakage in the pressure reducing valve 5 and the back pressure of the entire hydraulic system will increase the system back pressure behind the check valve 4', and the reversing valve 3 itself will leak a small amount to the lock valve 2 Hydraulic oil, under the combined action of the two, the hydraulic oil will reach the lock valve 2 through the three-position reversing valve 3, so that the oil cylinder 1' forms a differential cylinder, and the oil cylinder 1' protrudes outward at this time, causing the work Misoperation of bucket swing

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