Lining trolleys, primarily used in tunnel construction for the secondary lining process, are critical pieces of equipment that ensure the quality, efficiency, and safety of concrete lining. Their design specifications are complex and tailored to the specific demands of tunneling projects.

Lining Trolley Design Specifications

I. Core Functions and Types

Before diving into specifications, it’s crucial to understand the fundamental roles and variations of lining trolleys:

Primary Function: To support the formwork (shuttering) for cast-in-place concrete linings, or to position and install precast concrete segments for the inner wall of a tunnel. They help achieve the required surface shape, size, and finish of the tunnel lining.

Types (based on functionality, tunnel shape, and construction method):

Cast-in-Place (CIP) Trolleys: Most common, these carry large steel formwork sections. Concrete is pumped behind the formwork, and once cured, the trolley strips the formwork and moves to the next section.

Full-Round Formwork Trolley: For circular or near-circular tunnels, supporting the entire cross-section (invert, walls, arch).

Arch (or Crown/Sidewall) Formwork Trolley: For horseshoe or D-shaped tunnels, where the invert is cast separately.

Telescopic Formwork Trolley: Sections retract inwards for efficient movement through previously cast lining.

Precast Segmental Lining Trolleys (Segment Erectors): Used in TBM (Tunnel Boring Machine) tunnels, they transport, position, and install precast concrete segments.

Self-Propelled vs. Towed: Some have their own drive systems, others are moved by external machinery.

Rail-Mounted vs. Wheeled: Depending on the tunnel floor conditions and required stability.

II. Key Design Specifications and Considerations

The design of a lining trolley must balance structural integrity, operational efficiency, adaptability, and safety.

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For more detailed information on the design specifications for lining carts, please click here:https://www.gf-bridge-tunnel.com/a/blog/lining-trolley-design-specifications.html

Abnormal noise in a double-row ball slewing bearing can indicate a range of issues, from minor lubrication problems to significant component damage. Addressing the noise promptly is crucial to prevent further damage and ensure the longevity of the bearing and the machinery it supports.

Diagnosis of abnormal noise of double-row ball slewing bearing

Here are the common methods to solve abnormal noise in double-row ball slewing bearings, categorized by their underlying causes.

I. Addressing Lubrication Issues:

Insufficient Lubrication: This is one of the most common causes.

Solution: Regularly add the appropriate type and amount of grease. Follow the manufacturer’s recommended lubrication schedule. If the bearing has been dry for a while, it may require more frequent lubrication initially.

Poor Quality or Aged Grease: Grease can degrade over time, losing its lubricating properties.

Solution: Clean out the old, contaminated, or degraded grease and replace it with fresh, high-quality lubricant suitable for the bearing’s operating conditions (temperature, load, speed).

Uneven Grease Filling: Inadequate or uneven distribution of grease can lead to localized friction and noise.

Solution: Ensure the grease is evenly distributed throughout the raceway during lubrication. Running the bearing for a few rotations after greasing can help with distribution.

II. Resolving Contamination and Debris Problems:

Foreign Particles: Dirt, dust, metal shavings, or other debris entering the bearing can cause friction, wear, and noise. This often results in a “dust sounding” or “rattling” noise.

Solution: Disassemble the bearing (if feasible and necessary), thoroughly clean the raceway and rolling elements, and remove all foreign matter.

Prevention: Improve sealing arrangements to prevent contaminant ingress. Regularly clean the surrounding area of the bearing.

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For more detailed information on how to resolve abnormal noise in double row ball slewing bearings, please click heren: https://www.mcslewingbearings.com/a/news/double-row-slewing-bearing-noise-diagnosis.html

Replacing a double-row ball slewing bearing is a complex and critical procedure that typically requires specialized knowledge, equipment, and adherence to manufacturer guidelines. It’s not a DIY job for most individuals, especially given the heavy machinery and safety implications involved.

This is a general overview, and you MUST consult the specific manufacturer’s manual for your equipment and bearing model for precise instructions and safety protocols.

Double-row Ball Slewing Bearing Replacement

I. Pre-Replacement Assessment and Preparation:

Safety First:

Disconnect Power: Ensure the machinery is completely de-energized and all power sources are locked out/tagged out.

Secure the Load: If the bearing supports a structure (e.g., crane boom, excavator arm), secure it properly to prevent accidental movement.

Personal Protective Equipment (PPE): Wear appropriate PPE, including hard hat, safety glasses, gloves, and steel-toed boots.

Stable Position: Ensure the entire machine is in a stable position before starting any work.

Assessment of Existing Bearing:

Thoroughly inspect the old bearing for signs of wear, damage, corrosion, or any other issues that might have led to its failure. This can provide insights into potential root causes.

Check for loose bolts, seal integrity, and any abnormal noises or movements.

Gather Necessary Tools and Equipment:

Heavy-duty lifting equipment (cranes, forklifts, hoists).

Torque wrenches (calibrated for high torque values).

Specialized tools for removing and installing large bolts.

Feeler gauges for checking flatness and gaps.

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For more information on how to replace double row ball slewing bearings, please click here:https://www.mcslewingbearings.com/a/news/double-row-ball-slewing-bearing-replacement.html

Seismic design of steel structures is based on several key principles aimed at ensuring life safety, minimizing damage, and maintaining functionality during and after an earthquake. These principles leverage the inherent properties of steel, such as its strength and ductility.

Seismic Design Principles for Steel Structures

Ductility and Energy Dissipation (Inelastic Behavior):

It’s generally not economical to design structures to remain purely elastic during a major earthquake. Instead, the design philosophy allows for controlled inelastic deformation (yielding) in specific, pre-determined locations within the structure.

Steel is an excellent material for this due to its high ductility, meaning it can deform significantly beyond its elastic limit without fracturing.

This inelastic deformation dissipates seismic energy, reducing the forces transmitted to the rest of the structure and the building’s contents.

This is often achieved through the formation of “plastic hinges” in beams or other designated “fuse” elements.

Capacity Design:

This is a crucial principle that ensures a hierarchy of strength within the structural system. The idea is to force inelastic action (energy dissipation) to occur in ductile elements (e.g., beams, special connections) while ensuring that brittle elements (e.g., columns, foundations, critical connections) remain elastic and retain their strength.

This prevents a sudden and catastrophic collapse. For instance, in moment-resisting frames, the “strong column-weak beam” concept is applied, where columns are designed to be stronger than the beams framing into them, ensuring that plastic hinges form in the beams rather than the columns.

Redundancy:

A redundant structural system provides multiple load paths, meaning if one element or path fails, the loads can be redistributed to other elements, preventing progressive collapse. This enhances the overall robustness of the structure under seismic loading.

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For more detailed information on the principles of seismic design for steel structures, please click here:https://www.meichensteel.com/a/news/seismic-design-principles-for-steel-structures.html

The cost per square meter for a steel structure workshop can vary significantly, ranging from as low as $10 to $25 per square foot (approx. $107-$269 per square meter) for basic kits, to $20 to $50 per square foot (approx. $215-$538 per square meter) for fully installed prefab buildings, and even $50 to $200+ per square foot (approx. $538-$2150+ per square meter) for custom-built or industrial-grade structures.

Factors affecting the price of steel structure workshop

1. Material Prices:

Steel market fluctuations: Global demand, tariffs, and local availability directly impact the price of steel.

Type and quality of steel: Higher-grade steel offers better durability and strength but comes at a higher cost.

Auxiliary materials: Costs for bolts, welding materials, coatings, insulation, roofing, and foundation materials also add up.

2. Design Complexity and Customization:

Standard vs. custom designs: Simple, standard structures are generally less expensive than custom designs with unique features, layouts, or aesthetics.

Building dimensions: Larger buildings require more materials, but often benefit from economies of scale, leading to a lower cost per square foot for very large structures. However, buildings above a certain width (e.g., 32 feet) may require additional structural support (webbed trussing), increasing costs.

Features and accessories: The number of doors, windows, internal walls, mezzanines, skylights, specialized wall panels, and roof styles (e.g., vertical siding vs. horizontal) all add to the material and labor costs.

Load requirements: Designs that need to withstand specific snow loads, wind loads, or seismic loads will affect the structural design and materials used, increasing costs.

3. Labor Costs:

Regional labor rates: These can vary significantly by location.

Skilled labor availability: Shortages in skilled labor can drive up wages.

Construction difficulty: Complex designs or challenging site conditions can increase labor hours.

Pre-engineered metal buildings (PEMBs): These often speed up assembly and can help lower labor costs compared to traditional construction.

DIY construction: For smaller buildings, this can save on labor but requires expertise.

4. Location and Site Preparation:

Geographical location: Material prices, labor costs, and tax policies differ by region. Remote locations may also incur higher transportation costs.

Site accessibility: Difficult-to-access sites can increase delivery and construction costs.

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More about steel structure factory building price comparisons: What affects the cost per square meter? For detailed information, please click to visit:https://www.meichensteel.com/a/news/factors-affecting-the-price-of-steel-structure-workshop.html