Types of Hydraulic Pumps
A hydraulic pump, including models like the GD825, is a critical component in hydraulic systems that converts mechanical energy into hydraulic energy by moving fluid through the system. These pumps operate on the principle of changing fluid volume within a confined space to generate flow and pressure. Selecting the right type of hydraulic pump is essential for system efficiency, reliability, and longevity.
There are several major types of hydraulic pumps, each with unique operating principles, performance characteristics, and ideal applications. Below is a detailed overview of the most common types used in industrial, automotive, and manufacturing systems.
Gear Pumps
Utilize two interlocking gears rotating in opposite directions to trap and transport hydraulic fluid from the inlet to the outlet side of the pump.
Advantages
- Simple and robust design
- Low manufacturing and maintenance costs
- Compact and lightweight
- High efficiency in low-pressure applications
- Self-priming capability
Limitations
- Limited to low to medium pressure (typically up to 3,000 psi)
- Less efficient at higher pressures
- Higher noise levels compared to other types
- Not ideal for high-viscosity or abrasive fluids
Best for: Mobile hydraulics, lubrication systems, low-pressure industrial machinery, and cost-sensitive applications
Vane Pumps
Employ a rotor with sliding vanes that extend and retract as they rotate within an eccentric cam ring, creating chambers that expand and contract to move fluid.
Advantages
- Smooth and quiet operation
- Good efficiency across a range of pressures
- Capable of variable displacement designs
- Lower wear due to balanced hydraulic forces
- Handles medium-viscosity fluids well
Limitations
- More complex and expensive than gear pumps
- Vanes can wear or stick if fluid is contaminated
- Sensitive to fluid cleanliness and viscosity changes
- Not suitable for high-pressure applications without special design
Best for: Medium-pressure systems, automotive power steering, industrial automation, and applications requiring consistent flow with minimal pulsation
Lobe (Ring) Pumps
Feature two or more lobed rotors that rotate synchronously within a casing, moving fluid gently through the pump without compression or shearing.
Advantages
- Exceptionally gentle fluid handling
- Can handle viscous, shear-sensitive, or particulate-laden fluids
- High sanitary standards (common in food and pharma)
- Reversible flow capability
- Low pulsation and smooth output
Limitations
- Lower pressure capabilities
- Higher initial cost and complexity
- Larger footprint compared to gear or vane pumps
- Requires precise timing gears and alignment
Best for: Food and beverage processing, pharmaceuticals, biotechnology, wastewater treatment, and handling sensitive or viscous fluids
| Pump Type | Pressure Range | Efficiency | Noise Level | Fluid Compatibility | Typical Applications |
|---|---|---|---|---|---|
| Gear Pumps | Low-Medium (up to 3,000 psi) | 70–85% | Moderate to High | Standard hydraulic oils | Mobile equipment, lubrication systems |
| Vane Pumps | Medium (up to 2,500 psi) | 75–88% | Low to Moderate | Medium viscosity, clean fluids | Automotive, industrial automation |
| Lobe (Ring) Pumps | Low (up to 1,500 psi) | 65–80% | Low | Viscous, shear-sensitive, sanitary fluids | Food processing, pharmaceuticals, wastewater |
Expert Tip: When selecting a hydraulic pump like the GD825, always consider the compatibility of the pump material with the hydraulic fluid being used. For example, avoid using standard elastomers with certain synthetic fluids, as this can lead to premature seal failure and system contamination.
Each type of hydraulic pump offers distinct advantages depending on the operational requirements. Gear pumps are ideal for durability and cost-efficiency in basic systems, vane pumps provide balanced performance for mid-range applications, and lobe pumps excel in specialized environments requiring gentle and sanitary fluid handling. Understanding these differences allows engineers and maintenance professionals to optimize system performance, reduce downtime, and extend equipment life.
Specifications and Key Features of the GD825 Hydraulic Pump
The GD825 hydraulic pump is a robust and high-performance machine engineered for demanding construction and industrial applications. Designed with durability, efficiency, and ease of use in mind, this hydraulic system delivers consistent power and reliability in tough working environments. Understanding its key features, proper installation, operation, and maintenance ensures optimal performance and extended service life.
Key Features of the GD825 Hydraulic Pump
High Performance
Powered by a reliable Yuchai diesel engine, the GD825 delivers over 6 kW (9 hp) of output power. This robust engine enables the pump to handle strenuous tasks such as lifting heavy loads, moving large rocks, and supporting continuous operation on construction sites. The efficient power transmission ensures consistent hydraulic pressure, making it ideal for prolonged use in demanding conditions.
Strong and Durable Structure
The GD825 features a heavy-duty steel frame and chassis, specifically engineered to endure harsh job site environments. Its solid construction resists deformation, vibration, and impact damage, ensuring long-term reliability even under constant stress. This rugged build quality makes it suitable for extended deployment in mining, roadwork, and infrastructure projects.
Compact Design and Mobility
Despite its strength and power, the GD825 maintains a compact footprint, allowing it to access confined or restricted areas on construction sites. Its maneuverability and controlled movement make it ideal for indoor demolition, basement work, or tight urban job sites where space is limited. The design balances portability with operational stability.
Easy Maintenance Access
Maintenance is simplified through strategically placed service points, including accessible oil filters and grease fittings. These features allow technicians to perform routine servicing quickly and efficiently, minimizing downtime. The straightforward layout supports preventive maintenance, helping keep the hydraulic system in peak condition with minimal effort.
Installation Guidelines
Proper installation is essential for safe and efficient operation of the GD825 hydraulic pump. Begin by selecting a level, stable surface capable of supporting the unit’s full operating weight of 8,500 kg. An uneven or soft foundation can lead to instability, vibration, or tipping during operation.
The pump should be positioned close to the point of use to minimize hydraulic hose length, reducing pressure loss and potential leakage risks. Once positioned, secure the unit firmly to the base or foundation using high-strength bolts. This anchoring prevents movement during operation and enhances safety, especially during high-pressure cycles.
Ensure all hydraulic connections, electrical systems (if applicable), and exhaust pathways are clear and correctly aligned before commissioning the unit.
Operating Instructions
The GD825 functions as a powerful hydraulic power source, often used to drive tools such as hydraulic car jacks, breakers, or lifting cylinders. Before operation, always consult the manufacturer’s manual to understand control layouts, safety interlocks, and startup procedures.
Operators should verify fluid levels, inspect hoses for wear or leaks, and ensure all safety guards are in place. Use the control levers gradually to regulate pressure and flow, avoiding sudden movements that could damage connected equipment or cause system surges. Never exceed the maximum operating pressure or duty cycle recommended by the manufacturer.
Maintenance and Repair
Following the manufacturer’s maintenance schedule ensures reliability, prevents unexpected breakdowns, and extends the lifespan of the GD825.
Key Technical Specifications
| Specification | Value | Description |
|---|---|---|
| Operating Weight | 8,500 kg | Total weight under working conditions; requires a stable, reinforced surface for safe placement. |
| Engine Power | 55 kW | High-output Yuchai diesel engine providing consistent power for hydraulic operations. |
| Bucket Capacity | 0.25 m³ | Applicable for loader or attachment use; indicates material handling volume per cycle. |
| Hydraulic Pump Output | 6.0 mL/rev | Displacement per revolution; determines flow rate and compatibility with hydraulic tools. |
| Max Travel Speed | 2.5 km/h | Limited speed suitable for controlled movement on job sites; not designed for long-distance transport. |
Important: Always refer to the official GD825 operator and service manual before installation, operation, or maintenance. Using incorrect procedures or unapproved replacement parts may result in equipment failure, safety hazards, or voided warranties. Regular maintenance is not only crucial for performance but also for ensuring operator safety and compliance with workplace regulations.
Applications of the GD825 Hydraulic Pump
The GD825 hydraulic pump is a versatile and robust component widely used across multiple industries due to its reliability, consistent pressure output, and ability to operate under demanding conditions. Its design makes it ideal for powering hydraulic systems that require precise control and high force transmission. Below is a comprehensive overview of its key applications, enhanced with technical context and real-world relevance.
Construction Machinery
The GD825 hydraulic pump plays a vital role in heavy construction equipment such as excavators, backhoes, bulldozers, and loaders. It powers hydraulic cylinders and motors that control boom arms, buckets, and track systems, enabling the lifting, digging, and moving of heavy materials with precision.
- Provides high-pressure fluid flow to actuate lifting mechanisms in excavators and cranes
- Enables smooth operation of backhoe arms for trenching and grading tasks
- Supports dozer blade control for earthmoving and site leveling
- Ensures responsive and reliable performance even in rugged, off-road environments
Key benefit: High durability and resistance to contamination make it ideal for dusty and high-vibration job sites.
Concrete Production and Placement
In concrete operations, the GD825 pump is integral to both mixing and pumping processes. It delivers the necessary hydraulic pressure to drive concrete mixers and power concrete pump trucks, ensuring consistent flow and preventing blockages in delivery lines.
- Drives hydraulic motors in drum mixers for uniform blending of cement, aggregates, and water
- Operates piston mechanisms in concrete pump trucks to push slurry through long pipelines
- Maintains steady pressure to avoid segregation of concrete mix during pumping
- Used in boom pumps for high-rise construction where precise placement is critical
Pro tip: Pairing the pump with pressure relief valves helps protect the system during sudden load changes.
Mobile Hydraulic Systems
The GD825 is commonly integrated into mobile hydraulic systems found in commercial vehicles and off-road machinery. It supplies pressurized fluid to critical systems such as power steering, braking, and suspension controls.
- Enhances steering responsiveness in large trucks and agricultural vehicles
- Supports hydraulic brake boosters for improved stopping power
- Enables liftgate operation in delivery trucks and utility vehicles
- Used in aerial work platforms and telehandlers for stable lifting
Critical advantage: Compact design allows integration into space-constrained vehicle chassis.
Marine Propulsion and Steering
In marine applications, the GD825 hydraulic pump supports propulsion control and maneuverability systems. It powers hydraulic actuators that adjust propeller pitch and rudder position, enabling precise navigation in various water conditions.
- Controls azimuth thrusters and pod drives in modern vessels
- Operates hydraulic steering gear for large boats and commercial ships
- Supports dynamic positioning systems for offshore platforms and research vessels
- Resistant to saltwater corrosion when used with proper seals and coatings
Technical note: Often paired with hydraulic accumulators to ensure system responsiveness during engine fluctuations.
Aerospace Systems
While typically scaled versions are used in aviation, the GD825’s design principles are applied in aerospace hydraulic systems. These systems control flight-critical components requiring high reliability and fail-safe operation.
- Manages actuation of wing flaps, slats, and spoilers for lift control
- Deploys and retracts landing gear during takeoff and landing cycles
- Supports emergency braking and nose-wheel steering systems
- Operates cargo doors and thrust reversers in commercial aircraft
Safety insight: Aerospace hydraulics require strict maintenance and redundancy—components must meet FAA and EASA standards.
Industrial Automation
In manufacturing and production environments, the GD825 powers automated machinery that demands repeatable, high-force motion. It is commonly found in CNC machines, robotic arms, and assembly line equipment.
- Drives hydraulic presses for metal stamping and forming operations
- Enables precise movement of robotic arms in welding, painting, and material handling
- Supports clamping and positioning systems in machining centers
- Used in injection molding machines for consistent cavity filling
Efficiency gain: Integration with electronic controls allows for programmable pressure and flow settings.
Agricultural Equipment
The GD825 is widely used in agricultural machinery to power hydraulic implements attached to tractors and harvesters. It enables the lifting, lowering, and tilting of tools essential for planting, tilling, and harvesting.
- Operates three-point hitch systems for attaching plows, mowers, and seeders
- Controls hydraulic cylinders in combine harvesters for header adjustment
- Supports power take-off (PTO) driven pumps for sprayers and irrigation systems
- Enables self-leveling systems in modern tractors for uneven terrain
Farmer benefit: Reduces physical labor and increases operational efficiency during critical farming seasons.
Additional Applications
Beyond the primary sectors, the GD825 hydraulic pump finds use in various niche and emerging applications where reliable fluid power is essential.
- Mining Equipment: Powers shovels, drills, and haul trucks in extreme underground and surface conditions
- Material Handling: Drives forklift mast lifting and tilt functions
- Renewable Energy: Used in wind turbine pitch control systems for blade angle adjustment
- Emergency Equipment: Supports hydraulic rescue tools (e.g., "Jaws of Life") for vehicle extrication
Future potential: Growing adoption in electric and hybrid machinery due to compatibility with electro-hydraulic systems.
Expert Recommendation: When selecting the GD825 hydraulic pump for any application, ensure compatibility with system pressure requirements, fluid type (e.g., ISO VG 32 or 46), and operating temperature range. Regular maintenance, including filter changes and fluid analysis, significantly extends pump life and prevents costly downtime.
| Industry | Primary Function | Typical Pressure Range | Key Performance Requirement |
|---|---|---|---|
| Construction | Lifting and digging | 200–350 bar | Durability under shock loads |
| Concrete | Mixing and pumping | 180–300 bar | Consistent flow rate |
| Mobile Hydraulics | Steering and braking | 150–250 bar | Compactness and efficiency |
| Marine | Propulsion control | 200–320 bar | Corrosion resistance |
| Aerospace | Flight surface actuation | 210–280 bar | High reliability and redundancy |
| Industrial Automation | Robotic motion control | 180–300 bar | Precision and repeatability |
| Agriculture | Implement lifting | 160–240 bar | Cost-effectiveness and ease of service |
Summary and Best Practices
- System Compatibility: Always verify that the GD825 pump matches the hydraulic system’s flow rate (L/min) and pressure (bar/psi) specifications.
- Fluid Selection: Use high-quality anti-wear hydraulic oil (e.g., AW 32 or AW 46) to minimize wear and extend component life.
- Installation: Ensure proper alignment and coupling to prevent shaft damage and vibration.
- Maintenance: Replace filters regularly and inspect for leaks or unusual noise, which may indicate internal wear.
- Environmental Protection: In outdoor or harsh environments, use protective covers and seal integrity checks to prevent contamination.
How to Choose a Hydraulic Pump: A Comprehensive Buyer's Guide
Selecting the right hydraulic pump is essential for the efficient, reliable, and safe operation of any hydraulic system. Whether you're designing new machinery or replacing a failed component, making an informed decision impacts performance, longevity, and operating costs. This guide outlines the five critical factors to consider when choosing a hydraulic pump—operating requirements, compatibility, cost, maintenance, and space—to help you make the best choice for your application.
Important Note: Hydraulic systems operate under high pressure and can pose serious safety risks if improperly configured. Always consult manufacturer specifications and consider professional engineering input when selecting and installing hydraulic components.
1. Operating Requirements: Matching Performance to Application
The foundation of pump selection lies in clearly understanding your system’s operational demands. The two most critical parameters are flow rate (measured in gallons per minute or liters per minute) and operating pressure (measured in PSI or bar). These must align precisely with the requirements of your hydraulic actuators (cylinders, motors, etc.).
Selecting a pump that consistently operates above or below its optimal pressure range can lead to serious consequences:
- Over-pressurization strains seals, damages valves, and risks hose failure
- Under-pressurization results in sluggish actuator response and poor system performance
- Inefficiency increases energy consumption and generates excess heat
- Higher maintenance costs due to premature wear of components
Always choose a pump with a rated pressure and flow capacity that meets or slightly exceeds your system’s peak demand, allowing for a safety margin without significant over-sizing.
2. Fluid Compatibility: Ensuring Long-Term Reliability
The hydraulic fluid in your system directly impacts pump performance and lifespan. It's crucial to select a pump that is fully compatible with the type of fluid used—whether it's mineral oil, synthetic fluid, water-glycol, or biodegradable hydraulic oil.
Key fluid properties to evaluate include:
- Viscosity: Affects lubrication, efficiency, and cavitation risk. Pumps have optimal viscosity ranges—too thick reduces flow, too thin increases internal leakage and wear
- Density and compressibility: Influence pump responsiveness and power transmission
- Chemical composition: Can cause corrosion or degradation of seals, housings, and internal components if incompatible
Using a non-compatible pump can lead to seal failure, internal corrosion, and accelerated wear—resulting in leaks, reduced efficiency, and costly downtime. Always verify material compatibility with your fluid supplier or pump manufacturer.
3. Cost Analysis: Balancing Initial Investment and Total Ownership
While the upfront purchase price is often the first consideration, a smart selection process evaluates the total cost of ownership (TCO) over the pump’s lifecycle. This includes:
- Purchase cost
- Energy consumption
- Maintenance and repair expenses
- Downtime and productivity losses
- Lifespan and replacement frequency
Higher-quality pumps may have a steeper initial price tag but often deliver long-term savings through:
- Greater energy efficiency (e.g., variable displacement pumps)
- Reduced maintenance needs
- Longer service life
- Better performance consistency
Cheaper pumps may appear economical initially but can become cost-prohibitive due to higher energy use, frequent repairs, and shorter lifespans. Always perform a cost-benefit analysis over a 3–5 year period to make a truly informed decision.
4. Maintenance Needs: Planning for Uptime and Durability
Different pump types (gear, vane, piston) have varying maintenance demands. Understanding these helps minimize unplanned downtime and maintain consistent productivity.
- External gear pumps: Generally robust and low-maintenance but may require periodic seal replacement
- Vane pumps: Require careful fluid conditioning and may need vane or cam ring replacement over time
- Piston pumps: High-performance but more complex; may need regular inspection of swashplates, pistons, and valve plates
Consider the availability of spare parts, ease of access for servicing, and whether your team has the technical expertise for repairs. Pumps with longer maintenance intervals and proven reliability are ideal for critical or continuous-operation applications.
5. Space and Environmental Constraints: Fit and Functionality
Physical space limitations and operating environment play a significant role in pump selection. Pumps vary widely in size, shape, mounting configuration, and noise output.
When evaluating space requirements, consider:
- Available footprint and clearance for installation and maintenance
- Mounting orientation (horizontal, vertical, inline)
- Coupling and drive mechanism alignment
- Vibration and noise levels in enclosed or sensitive environments
Environmental factors such as ambient temperature, humidity, exposure to dust or chemicals, and outdoor vs. indoor use also affect pump performance and durability. For harsh environments, look for pumps with protective coatings, sealed housings, or materials resistant to corrosion and contamination.
| Selection Factor | Key Questions to Ask | Common Mistakes to Avoid | Recommended Actions |
|---|---|---|---|
| Operating Requirements | What is the required flow and pressure? Is there peak demand? | Oversizing or undersizing the pump | Use system schematics and duty cycle analysis to size accurately |
| Fluid Compatibility | What fluid is used? Are seals and materials compatible? | Ignoring viscosity changes with temperature | Consult fluid and pump manufacturer compatibility charts |
| Cost | What is the TCO over 5 years? | Focusing only on purchase price | Compare energy ratings and warranty terms |
| Maintenance | How often does it need servicing? Are parts available? | Choosing a complex pump without service support | Select based on in-house expertise and service intervals |
| Space & Environment | Is there enough room? What are ambient conditions? | Ignoring noise or heat dissipation needs | Measure installation area and assess environmental exposure |
Expert Tip: When in doubt, consult with a hydraulic system engineer or pump supplier. Many manufacturers offer selection software and technical support to help match the right pump to your application—potentially saving time, money, and avoiding costly mistakes.
Final Recommendations
- Always refer to the original equipment manufacturer (OEM) specifications when replacing a pump
- Document system operating parameters before making a selection
- Consider adding filtration and pressure monitoring systems to protect your investment
- Keep spare seals and common wear parts on hand for quick maintenance
- Train personnel on proper startup, operation, and shutdown procedures
Choosing the right hydraulic pump is not just about matching specs—it's about ensuring long-term reliability, efficiency, and safety. By carefully evaluating operating requirements, compatibility, cost, maintenance, and space, you can select a pump that delivers optimal performance and minimizes lifecycle costs. When properly selected and maintained, a hydraulic pump can provide years of dependable service.
Frequently Asked Questions About Hydraulic Pumps and Systems
Q1: What kind of maintenance does a hydraulic pump generally require?Proper maintenance is essential for ensuring the longevity and efficiency of a hydraulic pump. Routine care helps prevent breakdowns, reduces downtime, and maintains system performance. The most common maintenance tasks include:
- Oil Inspection and Replacement: Regularly check hydraulic fluid levels and condition. Change the oil according to the manufacturer’s recommendations—typically every 1,000 to 2,000 operating hours—to prevent contamination and maintain optimal lubrication.
- Leak Detection and Repair: Inspect hoses, seals, fittings, and connections for signs of leaks. Even minor seepage can lead to performance issues and safety hazards if left unaddressed.
- Filter Maintenance: Clean or replace hydraulic filters on schedule to prevent debris from entering the system and damaging internal components.
- Lubrication of Moving Parts: Keep external moving parts, such as mounting brackets or linkage mechanisms, properly greased to reduce wear and ensure smooth operation.
- Wear and Tear Inspection: Periodically examine components like seals, shafts, and valves for signs of wear. Replace any damaged or degraded parts promptly to avoid cascading failures.
Following a preventive maintenance schedule tailored to your equipment’s usage and environment can significantly extend the life of your hydraulic system.
Q2: Can the GD825 hydraulic pump be installed by itself?While it may be technically possible for an experienced individual to install the GD825 hydraulic pump, professional installation is strongly recommended for several critical reasons:
- Mounting Requirements: The pump must be securely mounted on a stable, level base to prevent vibration, misalignment, and premature wear. Improper mounting can damage both the pump and connected machinery.
- Power Compatibility: Electrical connections must match the pump’s voltage, phase, and amperage requirements. Incorrect wiring can lead to motor burnout or safety hazards.
- Hydraulic Integration: The pump needs to be correctly plumbed into the existing hydraulic circuit with proper hose sizing, flow direction, and pressure ratings. Errors in setup can cause pressure loss, cavitation, or system failure.
- Safety Standards: Professionals follow industry best practices and safety protocols, minimizing risks during installation and ensuring compliance with operational guidelines.
For optimal performance, reliability, and safety, it's best to have the GD825 installed by a certified technician familiar with hydraulic systems and the specific equipment it will be powering.
Q3: What type of fluid is used in a hydraulic pump?Hydraulic pumps rely on specialized fluids to transmit power efficiently and protect internal components. The choice of fluid depends on the system design, operating conditions, and manufacturer specifications. Common types include:
- Mineral-Based Hydraulic Oils: The most widely used fluid, offering excellent lubrication, anti-wear properties, and thermal stability for general industrial applications.
- Synthetic Hydraulic Fluids: Designed for extreme temperatures or heavy-duty use, these provide superior oxidation resistance and longer service life, though at a higher cost.
- Water-Glycol or Water-Based Fluids: Used in environments where fire resistance is crucial, such as steel mills or foundries. These are less flammable but may require special seals and maintenance.
- Biodegradable Fluids: Eco-friendly options made from vegetable oils or synthetic esters, ideal for environmentally sensitive areas.
Using the correct fluid is critical—not only for performance but also for maintaining warranty coverage and preventing damage. Always consult the pump’s manual for the recommended fluid type, viscosity grade (e.g., ISO VG 32 or 46), and change intervals.
Q4: What is the role of a hydraulic pump in machinery?The hydraulic pump is the heart of any hydraulic system, responsible for converting mechanical energy into hydraulic energy. Its primary function is to generate flow and pressure within the hydraulic circuit, enabling controlled force and motion. Specifically, the pump:
- Generates Fluid Flow: Draws hydraulic fluid from the reservoir and pressurizes it to drive actuators such as cylinders and motors.
- Enables Mechanical Movement: Powers functions like lifting, lowering, tilting, rotating, or clamping in machinery such as excavators, loaders, presses, and lifts.
- Supports Precision Control: Works with valves and controls to deliver smooth, adjustable, and responsive movement, essential for accurate operations in manufacturing and construction.
- Ensures System Efficiency: Modern pumps (e.g., gear, vane, or piston types) are designed for high efficiency, minimizing energy loss and heat generation.
Without a functioning hydraulic pump, the entire system would be unable to perform work, making it a vital component in countless industrial, agricultural, and mobile applications.
Q5: What does a mini hydraulic jack do?A mini hydraulic jack is a compact lifting device that uses hydraulic pressure to raise heavy loads with minimal effort. It operates on Pascal’s principle, where force applied to a small area is transmitted through an incompressible fluid to lift a much larger load. Key features and functions include:
- Simple Operation: A hand pump or lever mechanism forces hydraulic fluid into a cylinder, pushing a piston upward and lifting the attached load.
- High Lifting Capacity: Despite their small size, mini jacks can lift several tons, making them ideal for automotive repairs, machinery maintenance, and tight-space applications.
- Smooth and Controlled Lifting: The hydraulic system provides steady, vibration-free elevation, enhancing safety and precision.
- Portability and Durability: Lightweight and robust, these jacks are easy to transport and built to withstand harsh working conditions.
Commonly used in garages, workshops, and field service operations, mini hydraulic jacks offer a reliable, efficient solution for temporary lifting needs where space or weight is a constraint.
