The bridge girder launching gantry is made up of main girder, trolley, front support, middle support, rear support, electrical system and hydraulic system

1. Main girder

Main girder is made up of two parts: triangle honeycomb girder at left and triangle honeycomb girder at right. Each part has a total length of about50m. section to section connected by pin roll. The two parts main girders are connected by middle hoop beam and connection framework

2. Trolley

Made up of longitudinal moving gear box, heightening section, transverse moving beam and rail, transverse moving gearbox, trolley rack, winch, pulley block, hanging beam and connection framework

Trolley is the lifting mechanism. lower longitudinal moving mechanism makes trolley moves on rail on main girder; upper transverse moving mechanism makes trolley move on lateral sliding beam and rail; winch can lift the precast girder; above three parts and trolley steel structure as an unity finish lifting, moving, dropping precast girder and installing boundary girder as well as lifting small articles to front abutment; matched hanging beam has a wide use range to lift T type girder as well as box girder

3. Support

Front, middle, rear support and rear bracket. Front support and rear bracket have telescopic functions

Front support consists of bracket, internal sleeve, outer sleeve, connection beam, rotating connector, transverse moving gearbox, transverse sliding rail, front connection frame, fixing device, rail clamping device, hydro-cylinder and pin shaft.

Middle support: as a rear-end support when bridge girder launcher begins to install a girder, it is made up of roller institution, core tray, half curved beam, driving gearbox, driven gearbox, fixing device, transverse sliding rail and pin shaft.

Rear support is located in rear part of main longitudinal girder, made up of bracket, internal sleeve and outer sleeve. It is a rear-end support of bridge construction machine and a support for replacing support leg when moving from one pier to next pier.

Installed between middle support and rear support, rear bracket consists of hanging mechanism, roller mechanism, internal sleeve, outer sleeve, hydro-cylinder and pin shaft. As a rear end support to make main girder move forward when bridge construction machine installs a girder, the rear bracket could move at bottom of main girder with hanging mechanism, drive main girder to move forwards smoothly with roller mechanism. The internal and external sleeves can adjust the height of rear bracket to better adapt to crossing piers on slope bridge.

4. Hydraulic system

Made up of two groups of independent hydraulic stations on rear support leg and rear bracket , multiple directional control valve, cylinder and oil way. Located at the bottom of main girder, two hydraulic stations provide power for telescopic support legs

5.?Electrical system

Made up of motor and control cabinet with power about 75kw,? connected by cable, guide line and motor. Two control cabinets are fixed separately on rear parts of main longitudinal girder and lifting trolley. Control cabinet on trolley controls movement of trolley motor, while that on longitudinal girder controls crane?s longitudinal and transverse movement.

The launching gantry belongs to heavy-duty machinery equipment, a small mistake can cause serious accident. Therefore , the operator must operate the machine seriously according to the safe operating rules. ZZHZ has very rich experience of producing bridge girder launching gantry, therefore, it tells us what are dangerous operations:

1)?lifting goods without supervising (precast box girder and guiding girder etc.)
2)?the bridge girder launching gantry lifts persons
3)?the person who operates? launching crane without license
4)?lift goods which is heavier than rated lifting capacity or the goods with unsure weight
5)?lift unbalanced load, or the goods are bound on the earth.
6)?Swing the load or lifting tools when the machine is traveling longitudinaly.
7)?The lifting tools are used as support for load.
8)?The steel rope is used as lifting rope for load
9)?The steel rope is used as grounding line when it is welded.

(1)Advantages

1. Honeycomb-girder (patented product) is first-made by Huazhong which enjoys a good fame in industry inside and outside

2. Light self-weight, large load, high wind-resistance and high rigidity, low deflection, so it is quite safe

3. Flexible legs, easy to transfer to another site

4. Reliable and unique pin connection, short-time installation

5. Imported and high-quality electronic components also ensure the safety of hand operation

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(1) General arrangements

1.Motor of HZY900 girder transporter is placed in rear part, frame girder in middle parts with 2 columns 16 axis, 2 wheels for each wheel set, 64 wheels in total;

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(1) Introduction

.Product name : HZY 900 girder transporter

Product model: HZY900

HZY—girder transporter series of ZZHZ(Zhengzhou Huazhong Construction Machinery Co., Ltd)

900—rated lifting capacity 900t

C—stands for engineering vehicles

1—26.5R25 tyre series

 

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Zhengzhou Huazhong Construction Machinery Co.?Ltd(ZZHZ) lies in Shangjie district of Zhengzhou city, Henan Province, China, Which enjoys convenient transportation and superior geography position. It was established Nov., 1992. Up to now, it has become a united running production corporation of China?s Construction Machinery Co., Ltd.
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?1. Design technical conditions

Rated lifting capacity????????????? 160t

Utilization grade????????????????? U5

Load condition??????????????????? Q2

Complete machine working level??????? A5

Institutions working level????????????? M4

Trolley track gauge?????????????????? 6.0

Trolley lifting speed with full load?????? ?0.9m/min

Trolley moving speed with full load????? ?2.75m/min

Moving speed for the complete machine to cross piers??? ?2.75m/min

Max wind pressure in working condition???? 250N/m²

Max wind pressure in non-working condition ^{??????????????????????}800N/m²

 

2. Safety factor and admissible casino spiele stress

Take load combination based on present national standard crane design code GB3811-83

Table 1????? material safety factor and admissible stress (MPa)

	material	Safety factor?n?	pull?press?bend???	Shear force???	Pressure-bearing??cd??
?type load combination	Q235	1.33	177	102	265
	Q345	1.33	259	150	386
?type load combination	Q235	1.15	205	118	308
	Q345	1.15	300	173	450

Note: if thickness of rimmed steel and structural steel > 15mm and thickness of steel plate > 20mm, the admissible stress should be multiplied by 0.95 to be reduced.

 

3. Allowable static deflection of bridge girder launcher frame [ f ]

Span L= 43m, middle span: [f]?43000/700?61.43mm

Span L= 30m, middle span: [f]?30/700?42.85mm

According to clause 3.8.1.1, crane design code GB3811-83, working level of bridge crane is A5 or below A5, Y_L?L/700;

 

As safe operation of the launching gantry is very important in the bridge construction, ZZHZ summarizes some tips to help workers operate the bridge girder launcher smoothly, for the sake of life safety and smooth construction.
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(1). Main technical parameters

Model HZQ30/80
Span （m） 30
Lifting capacity（T） 80
Total weight（T） about 105
Main girder honeycomb girder
Min curve radius（m） ≥400
Max allowable gradient（%）
longitudinal gradient≤±3%，
transverse gradient≤±4%
central distance between two girders（m） 7.0
lifting speed （m/min） 1.0
launcher longitudinal moving speed（m/min） 4.6
launcher transverse moving speed（m/min） 3.0
trolley longitudinal moving speed（m/min） 4.6
trolley transverse moving speed（m/min） 1.7
power（KW） about 75

(2). Configuration for HZQ30/80 bridge girder launcher (1 set)

item specification origin quantity remark
main girder: Steel structure ZZHZ 2 parts One side girder about 50m
Front support： Steel structure ZZHZ 1 set
Middle support： Steel structure ZZHZ 1 set
Rear bracket： Steel structure ZZHZ 1 set
Rear support： Steel structure ZZHZ 1 set
trolley： Steel structure ZZHZ 2 sets 40t×2=80t
Downstroke reducer of front support： XLED63-2.2KW China 2 sets Tapered spline brake
Downstroke reducer of middle support： XLED63-2.2KW China 2 sets Tapered spline brake
Lifting reducer： ZQ500-11KW China 2 sets Tapered spline brake
Longitudinal movement reducer of trolley： XLED63-2.2KW China 4 sets Tapered spline brake
Transverse movement reducer of trolley： XLED63-0.5KW China 4 sets Tapered spline brake
Driving hang reducer of support leg： GKF37- Y0.8-4P China 4 sets Tapered spline brake
Roller walking reducer： XLED63-2.2KW China 4 sets Tapered spline brake
Hydraulic station： ZZHZ 2 sets
Hydro-cylinder of front support： HSGK160-750 China 2 units With hydraulic lock
Hydro-cylinder of rear bracket： HSGK200-600 China 2 units With hydraulic lock
Electric element： Schneider 1 set

(3). About after-sales service

1.Quotation: USD 175,000 per set FOB Tianjin
2.Terms of payment: T/T, L/C
3.Quality warranty : 1 year quality warranty
4. Installation and commissioning
Our responsibility: We will send two technicians to guide you how to install and commission the bridge girder launcher, and they also help train your staff with free charges.
Your responsibility: you are responsible for their food and accommodation, salary and round trip tickets.
5.Time arrangement:Lead time: 65 days

One important operating principle for HZQ59/80 launching gantry electrical system is to do a movement at one time, then next action to avoid fault, it must be followed especially at starting and stopping operation.
It is strictly prohibited to adjust the movement of other systems if one system is working, especially prohibit to rotate the change-over switch.

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