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Pedrail crane removes the improvement of litre of hydraulic pressure system
From;    Author:Stand originally

The windlass compose of crane of a crawler uses a type to often shut brake, when carry for nothing or carrying promotion gently, brake cannot sufficient come away, make brake chafes piece be in slippery grind condition, cause windlass compose even acuteness vibration, make pound and its component is damaged extremely easily.

Breakdown case study
By attached drawing (A) knows, when litre of job having before improving, pressure oil moves reversal valve through the hand 6 hind cent is two, motor rises since the input all the way the left oil mouth of 2 enters crock of apply the brake another times.
Should rise rise since machine when load is largish, oil pressure of motor place casting can be more than brake open pressure (1.5~2MPa) , such brake can be opened completely first, next if have litre of load,motor rotates very small, motor drive load and the oily fluid pressure that overcome attrition obstruction place to need will be less than the open pressure of brake, the pressure when carrying promotion for nothing even is approximately 0, at this moment brake cannot be opened completely namely, because chafe piece cannot depart adequately and generation is slippery grind, ablation, more serious when can cause the impact with a raise strong system, vibration, cause structural member damage extremely easily.

Crane carries gently, when holding the job for nothing, its are the biggest torsion of static apply the brake is more than motor output torsion and make motor cannot turn, lift as systematic oil pressure, motor output torsion increases, torsion of the biggest static apply the brake reduces brake, till both the motor when achieving a balance begins roll. If can satisfy a requirement of raise system stability, criterion its can enter steady state very quickly, namely motor pressure is worth firmly on some, torsion of apply the brake is constant, attrition piece be in stability to slip grind condition, won't appear consequently concussion conversely, roll raise system will produce concussion and vibration. At this moment motor drives attrition piece begin to slide, torsion of apply the brake drops very quickly, motor is in instantaneous to quicken level to lift as motor rotate speed, oil pressure is reduced quickly, the result brings about motor output torsion is reduced and torsion of apply the brake increases, make motor is in instantaneous decelerate phase. When decelerate phases ends, lowest of motor rotate speed is even 0, accordingly motor inlet pressure can lift quickly again, and torsion of apply the brake can be reduced quickly again, form what the next circulates to accelerate rotational process. Such frequentative becomes oscillation, make coil vibration of raise system generation and concussion.

Pedrail crane removes the improvement of litre of hydraulic pressure system
To remove this one trouble, in attached drawing (a powerful person of the balance in removing litre of oil path of A) 3 before increase inside charge pattern one-way sequence valve 4, like attached drawing (B) place is shown, sequence valve open pressure is 2MPa. The hand when litre of hook should rising after improving moves reversal valve 6 be in left, reversal valve of pressure oily classics 6, one-way sequence valve 4, balance a powerful person 3 junior enter motor Zun Duan oily mouth. When carry for nothing or carrying gently, because one-way sequence valve increased in oil path 4, make the oil pressure that enters brake is 2MPa, brake can be opened adequately, won't appear unusual vibration and concussion phenomenon are become when load is bigger, systematic pressure is more than 2MPa far, because mouth of a powerful person opens this sequence valve completely,open, should choose only appropriate the one-way sequence valve that opens way, the pressure loss that causes in oil path is completely negligible. This is improved classics is long-term use result is favorable, did not appear again this kind of breakdown.
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