High Efficiency Easy Maintenance Double Girder Overhead Crane

• Certification: ISO9001
• Condition: New
• Operation Form: Air Operation+Ground Operation
• Model NO.: QD
• Maximum Lifting Height: >40m
• Maximum Lifting Weight: >200t
• Main Girder Form: Double Girder
• Type: Ordinary
• Transport Package: Sea Worthy Package
• Origin: China
• HS Code: 84261120
• Production Capacity: 500 Set / Year

Product Description

Over head crane technical introduction

1           Design standards
Crane design standards are state standards and applicable standards and requirements from user. 
1.1        Crane design, construction and inspection and test standards are as follows.
GB3811-83............ lift equipment design standard
GB/T14405-93...... general over head crane standard
GB/T14407............ general overhead crane and gantry crane operator cabin standard
GB6067-85............ lift equipment safety design standard
GB10183-88.......... over head crane and gantry crane construction and
rail installation tolerance
GB12602-90.......... lift equipment overload protective device standard
GB5905-86............ crane test standard
GB8918.................. steel rope standard
GB5972-86............ lift equipment steel rope inspection and desert standard
GB7592-87............ general over head crane dimension standard
GB8923-88............ steel surface rusty grade and rust deleting grade before painting treatment
SDZ 014................ general painting standard
GB9286-88............ colored paint and paint film case inscription test
GB1497-85............ low voltage electric apparatus standard
JB/DQ4658-91...... crane resistor set standard
JB/DQ6146-86...... crane control table
JB/ZQ2007-90...... crane electric circuit drawing standard
Q/DQ109-92.......... crane electric devices technical standard
JBZ299-78............. mines and project lift equipments paint color and safety signs
GB/T13384............ general electrical and mechanical product package
technical standard

ASEM and so on equivalent standard can also be followed for design, manufacture and testing.

1.2        General specification

No.	specification	number	note
1	QD20/5t-21m A6	1 set

2           Technical outline
Our company is a special crane maker. Designing work is done by engineering department. Crane computer aided design standards are based on user technical parameters and use environment conditions. Construction standard is GB/T14405.
3           Over head crane technical introduction
3.1        Steel structure
3.1.1     Bridge structure include main girder and end beam. Main girder is middle rail box girder with static rigidity less than s/800 within class A4 and class A6 and static rigidity less than s/1000 for class A7. Full loaded self-vibration frequency is no less than 2Hz.Out side of girder has walkway and guard rails. Crane travel devices and girder electric apparatus are set on walkway. Crane arrangement and profile is reasonable and beautiful.
3.1.2     End beam is box girder which is bolted with high strength bolts.
3.2        Crane mechanisms
3.2.1     In hoist mechanism,there are electric motors, brakes, couplings and transmission shafts, reducers and winding drum, steel wire and hook set, and stationary pulley.
  A. Winding drum is made of cast steel or rolled steel plate and steel wire flat angle is no more than 3.5°. There are at least two rounds of safety steel wire. Press pads and bolts are stable and reliable.
  B. Hoist mechanism has extreme position limit with rotary switch.
  C. Hoist mechanism has CLZ gear couplings; crane and trolley travel mechanism is CL and CLZ type.
3.2.2     Trolley travel mechanism
    Trolley is separate driving type. Wheel is double rim type and bumper is spring type.
3.2.3     Crane travel mechanism
    Crane is four-drive type, and wheel has double rims .Bearing shell is angle shape. Bumper is hydraulic anti-crash type.
3.3        Key components
3.3.1     Electric motor is YZP series with rated volt of 380 v and 50Hz, insulation degree is F grade and protective grade is IP44.This type of motor has bigger over load capacity and mechanical strength and is suitable to equipments which start and stop frequently or with over load and obvious vibration and crash.
3.3.2     Brake is YWZ series with hydraulic normal closed thruster, lift mechanism has manual release device. Brake has constant features, longer use life and ease of maintenance required in GB6333-86.
3.3.3     Reducer has ZQ type and ZSC type required in ZBJ19010.
3.3.4     Crane hook is forged material required by GB699-65 and GB1051.
3.3.5     Pulley material is HT150 cast required by ZBJ80006-87 and ratio of pulley and steel wire is no less than 22.4.
3.3.6     Winding drum is HT200 cast required by ZBJ80007-87
3.3.7     Steel wire of 6w(19) type is required by GB1102-74 with strength within 1400~1700N/mm².Safety factor from 5 to 7 should be applied according to mechanism class.
3.3.8     Wheels set standard is GB4628-84 and wheel material isZG50SiMn.Tread hardness is within HB300 and HB 380 and more than HB260 in depth of 20mm.
3.3.9     Material of brake wheel in lift mechanism is #45 steel at least in GB699.Brake wheel surface hardness is within HRC45 and HRC 5 5,and HRC40 in depth of 2mm.
3.3.10  Material of major components such as main girder and end beam and trolley frame meet standards of GB700-88 and GB1591-88 as follows.

Components		Significant components			Other components
Work ambient temperature		Above -20ºC		Above -20~25ºC	Above -25ºC
Work class		A1-A5	A6-A7	A1-A7	A1-A7
Material type	δ≤20mm	Q235-BF	Q235-B	Q235-D	Q235-AF
	δ≥20mm	Q235-B	Q235-C	16Mn

4           Crane main craftsmanship
4.1        Raw material with quality certificates is checked before coming into factory warehouse. Then random chemical-physical test should be carried out before storage in warehouse.  
4.2        Steel plate and section steel should be shot blasted to reach grade Sa2.5 for steel plate surface and grade S3 for section steel. Rust should be removed by using primer paint.
4.3        Refer to more detailed information for main components (main girder and end beam) process artwork
A. Cover plate and web plate butt weld should be submerged arc welding. Steel plate more than 10mm thick should be groove welding and weld should be ultra-sonic or x-ray  non-defects 100% inspected.
B. Cover plate and web plate cutting is with numerical controlled cut machine to obtain pre-deflection.
C. Longitudinal seam of main girder and end beam is welded with submerged arc welder or micro-controlled protective carbon dioxide welder.
D. Welding and assembly of bridge structure are done with large size platform and level welding.
5           Functional features
5.1        Crane static rigidity: for class A4-A6 crane with trolley and load in girder middle position, rigidity is less than s/800,for class A7 crane with trolley and load in girder middle position, rigidity is less than s/1000.
Static test: crane is loaded with 1.25Gn and 100mm-200mm above ground for more than 10 minutes. After load is released, main girder should have no permanent deformation in 3 test cycles.
5.2        Dynamic tests: trolley is loaded with 1.1 Gn to start and brake within travel distance of each action for at least 1 hour. Then, there should be no damage and linkage loose in all components and mechanism.
6           Protective functions
6.1        In power distribution protective system, there are main circuit breaker, main contactor and automatic switch in each mechanism. Distribution control has crane power activation and off switch and emergency switch, power source index, safety switch and limit switch. Main loop has circuit shortening, over load protection, volt loss protection and zero protection.
6.2        Limit switch of LX10-31 shall cut off power supply in hoist mechanism when hook approaches extreme point.
6.3        There are travel limit switches at ends of travel mechanisms.
6.4        There are also QCX-2 type overload limiter which has indication and acoustic-optic alarm and over load controls.
7           Safety protection
7.1        Emergency switches in control loop circuit shall cut off loop power supply in case of emergency.
7.2        Crane entrance door and inclining stair door and fence door are all interlocked and have safety switches. When one door is open, safety switch is off and then main contactor shall be disconnected automatically.
8           Trolley power supply
Trolley power is supplied through suspending soft cable under section steel.
9           Illumination and signal
9.1        There are separated transformer for signal and illumination. Original input line volt is 380 V and aux. output line volts are 220V and 36V. 220V is for crane illumination power and 36V is for crane signal and repair power.
9.2        Lights under girder are quake resistant 400w type.
9.3        Crane have start warning device controlled from operator cabin.
9.4        Crane have repair and check socket of AC 36V.
10         Others
10.1      Cables are arranged in raceway, and soft tube is used where raceway is impossible to reach.
10.2      Cables are high temperature proof and section is more than 1.5mm².
10.3      Power reception panel and control panel lines of different mechanisms use copper wire and copper bars.
10.4      There is 10%~15% stock allowance in control panel cable bus and power distribution panel and wiring box terminal. 
10.5      Main loop contactor in control panels of different mechanisms are both electrically and mechanically interlocked.