Elevators and Chain Elevators: A Guide to High-Vertical Conveyance
In industrial facilities, lifting raw materials to high elevations is just as important an engineering challenge as transporting them horizontally.
The system used for silo feeding, bunker filling, top-loading of process equipment, or product transfer between different floors must:
- provide sufficient capacity,
- minimize product breakage,
- operate with minimal energy consumption,
- be wear-resistant,
- and keep maintenance needs under control.
In this regard, bucket elevator systems are one of the most important mechanical conveying solutions used for transporting bulk materials over significant vertical distances.
In particular,
- grain,
- granules,
- pellets,
- minerals,
- cement,
- chemical raw materials,
- feed,
- fertilizer,
- and various powdered products
can be transported using bucket elevators with the appropriate equipment design.
However, not all elevators are the same.
Depending on the product to be transported and the process conditions,
- belt-type bucket elevators,
- chain-type elevators,
- single-chain,
- double-chain,
- centrifugal discharge,
- and continuous discharge
systems may be preferred.
Therefore, the correct question is not:
“How many meters will we lift it?” but rather, “Which elevator design can transport this product at the target capacity with acceptable product damage?”
This guide
In this guide, we will examine bucket elevator and chain elevator systems in detail in terms of operating principle, capacity, speed, bucket selection, chain/belt design, product behavior, wear, and maintenance.
What Is a Bucket Elevator?
A bucket elevator is a mechanical conveyor system used to transport bulk materials, particularly in a vertical direction.
Buckets spaced at regular intervals along the system pick up the product from the lower feed section and carry it upward inside the elevator body.
At the top section, the product is discharged at the outlet point with the help of:
- centrifugal force,
- gravity,
- and controlled flow.
A bucket elevator essentially consists of the following components:
- lower body / boot section,
- upper body / head section,
- intermediate body modules,
- buckets,
- chain or belt,
- drive system,
- drum or sprocket,
- tensioning mechanism,
- product inlet,
- product outlet.
The system design varies depending on the product’s characteristics.
How Does a Bucket Elevator Work?
The basic operating principle can be examined in four stages.
1. The product is fed into the elevator
The product to be transported can be fed into the lower body via:
- a screw conveyor,
- a chain conveyor,
- a belt conveyor,
- a hopper,
- or a star feeder.
The feed rate must be compatible with the elevator’s capacity.
The feed rate must be compatible with the elevator’s capacity.
2. The buckets pick up the product
Buckets passing through the lower section pick up the product.
The degree to which the buckets are filled with product may vary depending on:
- bucket geometry,
- speed,
- product flowability,
- and feed method.
3. The product is transported vertically
The buckets move upward on a belt or chain.
4. The product is discharged from the upper section
Once the product reaches the top, it is transferred to the discharge outlet according to the elevator design.
What Is a Chain Elevator?
A chain elevator is a type of bucket elevator in which the buckets are attached to one or more chains as the carrying elements.
Chain-driven systems are particularly suitable for applications requiring:
- heavy products,
- high temperatures,
- abrasive environments,
- heavy-duty service,
- and low- or medium-speed conveying.
In chain-driven bucket elevators, the buckets can be attached to:
a single chain,
- or a double chain.
- Double-chain systems can provide more stable conveying under heavy loads.
The Difference Between a Belt-Driven Bucket Elevator and a Chain-Driven Bucket Elevator
The Difference Between a Belt-Type Bucket Elevator and a Chain-Type Bucket Elevator
One of the most important design decisions is whether the carrying element should be a belt or a chain.
Criterion Belt Elevator Chain Elevator
Conveying element Belt Chain
Operating speed Generally higher Generally lower
Capacity Can be high Can be high
Heavy products Depends on the application May be more advantageous
High temperatures Belt may be a limiting factor May be more advantageous
Abrasive environments Requires a suitable belt Heavy-duty solution is possible
Maintenance Belt inspection is critical Chain and sprocket inspection is critical
Product breakage Depends on speed A low-speed design may offer advantages
Noise Generally lower May be higher
This table is for preliminary selection.
The final decision should be based on the product, capacity, and operating conditions.
In Which Cases Is a Chain Elevator Preferred?
Chain elevators are particularly strong candidates for the following processes:
- heavy bulk materials,
- high-temperature products,
- abrasive minerals,
- high mechanical loads,
- low-speed controlled conveyance,
- heavy-duty operating conditions.
For example, if a mineral or similar heavy product needs to be conveyed at high temperatures, a standard rubber belt may not be suitable.
In this case, a chain system should be considered.
In Which Situations Is a Belt Elevator Preferred?
Belt elevators can offer advantages particularly for:
- high speed,
- high capacity,
- light and medium-density bulk materials,
- grain,
- granules,
- feed,
- and certain powders
.
The lighter weight of the belt system can provide advantages in terms of energy consumption and high speed.
However, the belt must be selected based on conditions such as:
- temperature,
- oil,
- chemicals,
- and corrosive environments
.
How Is the Capacity of a Bucket Elevator Calculated?
The capacity of a bucket elevator is not determined by motor power alone.
In the basic capacity calculation,
- bucket volume,
- bucket fill ratio,
- bucket spacing,
- belt/chain speed,
- and product bulk density
are evaluated together.
In simplified terms, volumetric capacity can be calculated using the following logic:
Qv = V × F × N
Where:
- Qv: volumetric capacity
- V: effective volume of a bucket
- F: fill factor
- N: number of buckets passing per unit time
Mass capacity, on the other hand, can be calculated as:
Qm = Qv × ρ
where:
Here:
ρ = bulk density of the product
is the value.
Example Elevator Capacity Calculation
This calculation is only an illustrative example.
Let’s assume:
- effective bucket volume: 10 liters,
- fill factor: 70%,
- buckets passing per minute: 120,
- product bulk density: 800 kg/m³.
Effective product volume:
10 L × 0.70 = 7 L/bucket
Volume per minute:
7 × 120 = 840 L/min
This:
0.84 m³/min
means.
Theoretical hourly volume:
0.84 × 60 = 50.4 m³/h
If the product’s bulk density is 800 kg/m³:
50.4 × 800 = 40,320 kg/h
that is, theoretically:
40.3 metric tons/hour
is obtained.
However, the actual system capacity
- may be lower due to
- the feeding arrangement,
- bucket filling,
- product leakage,
- speed,
- discharge behavior,
and elevator geometry.
Therefore, the theoretical capacity should not be used directly for motor or equipment selection.
Why Is the Bucket Fill Ratio Important?
The geometric volume of the buckets is not the same as the actual amount of product they carry.
For example, a bucket with a volume of 10 liters does not always carry 10 liters of product.
The actual fill rate varies depending on:
- the product’s flowability,
- the elevator speed,
- the feeding method,
- the bucket geometry,
- and the product’s particle structure.
Therefore, the fill factor must be used in capacity calculations.
How Is a Bucket Selected?
A bucket should not be selected based solely on volume.
Criteria to consider:
Product density
For heavy products, the mechanical strength of the bucket and connecting components is important.
Particle size
For coarse products, the bucket opening and geometry may be designed differently.
Product Fragility
For delicate products, aggressive centrifugal discharge can increase product damage.
Abrasiveness
For mineral products, the hopper material and wall thickness are important.
Temperature
Plastic or standard materials may not be suitable at high temperatures.
Plastic Hopper or Metal Hopper?
Depending on the application, hoppers can be manufactured from:
- plastic,
- carbon steel,
- stainless steel,
- wear-resistant steel
.
Plastic hoppers
Advantages:
- lightweight,
- corrosion resistance,
- low noise,
- may be advantageous in grain and food applications.
Metal Buckets
Advantages:
- high mechanical strength,
- temperature resistance,
- suitability for heavy products.
Stainless Steel Buckets
They are particularly suitable for:
- food,
- chemical,
- and hygienic process
applications.
How Is Elevator Speed Determined?
Elevator speed directly affects capacity.
However, a higher speed does not always mean higher efficiency.
As speed increases:
- the number of buckets per unit time increases,
- capacity may increase,
but at the same time:
- the risk of product breakage,
- wear and tear,
- vibration,
- and improper discharge
may increase.
Especially with fragile products, increasing the speed excessively can lead to a loss of quality.
What Is a Centrifugal Discharge Bucket Elevator?
In some high-speed bucket elevators, as the product passes through the upper drum, it is flung toward the discharge opening due to the effect of centrifugal force.
This system is called a centrifugal discharge bucket elevator.
Advantages:
- high capacity,
- high speed,
- continuous transport.
However, product behavior must be evaluated separately for fragile or abrasive products.
What Is a Continuous-Discharge Elevator?
In low-speed systems, buckets can be positioned closer together.
The product can flow in a controlled manner from the outlet of one bucket along the back surface of the next.
This type of system can be considered for applications requiring:
- fragile products,
- heavy products,
- and more controlled discharge.
This approach is often preferred in chain elevators.
Why Is the Elevator Feed Point Important?
How the product is fed into the lower section of the elevator significantly affects performance.
Uncontrolled feeding can lead to:
- overfilling of the buckets,
- product buildup in the lower section,
- jamming of the elevator,
- and increased motor load.
For this reason, the capacity of upstream equipment must be adjusted according to the elevator’s capacity.
For example: Silo → Star Feeder → Bucket Elevator or Big Bag → Screw Conveyor → Bucket Elevator can be used for controlled feeding.
For example:
Silo → Star Feeder → Bucket Elevator
or
Big Bag → Screw Conveyor → Bucket Elevator
controlled feeding can be achieved in these configurations.
Why Do Bucket Elevators Clog?
Clogging in bucket elevators can occur for various reasons.
Excessive product feeding
is one of the most common causes.
Low discharge capacity
If the product cannot be discharged quickly enough from the upper section, it may accumulate.
Product adhesion
Moist or cohesive product may accumulate inside the buckets and the body.
Incorrect speed
The buckets may fail to deposit the product in the correct discharge area.
Foreign object
A foreign object entering the lower body of the elevator may jam the chain or the bucket.
What Is Elevator Backflow?
When the elevator stops, the weight of the product in the buckets and the moving system can cause the system to move in the opposite direction.
For this reason, in some systems:
- a backflow lock,
- a backstop,
- or a brake
may be used.
This safety component becomes critical, especially in tall elevators.
Why Does Chain Elongation Occur?
In chain elevators, chain elongation can occur over time.
The causes include:
- pin-bushing wear,
- insufficient lubrication,
- excessive load,
- incorrect tension,
- misalignment,
- corrosive environment.
As chain elongation progresses,
- problems such as improper engagement with the sprocket,
- vibration,
- impact,
- chain skipping
may occur.
What Should the Chain Tension Be?
A chain that is too loose or too tight causes problems.
A very loose chain
- may jump off the sprocket,
- may cause knocking,
- or may cause the buckets to contact the body.
A chain that is too tight
- can increase bearing loads,
- accelerate chain wear,
- and increase energy consumption.
For this reason, the tensioning mechanism must be checked regularly.
What Causes Belt Slippage in a Bucket Elevator?
One of the major malfunctions in belted systems is belt slippage.
Main causes:
- insufficient tension,
- contamination of the drum surface,
- excessive load,
- misalignment,
- belt wear.
If slippage persists for a long time, it can lead to:
- belt damage,
- loss of capacity,
- overheating
.
Why Is Belt Alignment Critical for Elevators?
When the belt drifts off-center:
- it may rub against the frame,
- bucket connections may be damaged,
- and the belt edges may wear out.
For this reason, belt tracking sensors and mechanical alignment are critical for elevator reliability.
In Which Areas Does Wear Occur in Elevators?
Especially with abrasive products, the following areas may be critical:
- lower body,
- product inlet,
- buckets,
- upper outlet,
- direction-changing surfaces.
In these areas,
- wear plates,
- replaceable liners,
- and wear-resistant steel
can be used.
Why Does Elevator Capacity Decrease?
If a system fails to maintain its nominal capacity over time, the following causes should be investigated:
- buckets not filling completely,
- reduced product feed rate,
- changes in belt/chain speed,
- clogged outlet,
- bucket wear,
- changes in product bulk density,
- slippage,
- chain elongation.
In particular, when product density changes, the same volumetric capacity translates to different metric tons per hour values.
Bucket Elevator or Pneumatic Conveying?
This comparison is particularly important for new plant investments.
Criterion Bucket Elevator Pneumatic Conveying
Vertical conveying Very powerful Suitable
Horizontal Conveying Limited Very flexible
High Capacity Depends on system type
Energy May be advantageous for vertical conveying Air generation requires energy
Route Fixed Flexible
Dust Control Enclosed housing required Enclosed pipe is advantageous
Moving Parts Many Few in the pipe line
Product Damage Depends on design Depends on speed/phase
A bucket elevator is a significant alternative, especially when the product needs to be transported only over a high vertical distance.
However, if the product must first be transported horizontally, then vertically, and then horizontally again, a pneumatic system may be more flexible.
This section should include an internal link to the Pneumatic Conveying Systems guide.
Bucket Elevator or Screw Conveyor?
Screw conveyors are used for short-distance transport.
The efficiency of a screw conveyor can drop significantly for high vertical transport.
The bucket elevator, on the other hand, is specifically designed for vertical transport.
Example:
3-meter horizontal transfer: The screw conveyor is a strong candidate.
25-meter vertical transfer: The bucket elevator is a strong candidate.
Bucket Elevator or Chain Conveyor?
These two systems operate under different geometries.
Bucket elevator:
Vertical transport.
Chain conveyor:
Typically horizontal or low-incline transport.
Both systems can be used together throughout the entire plant line:
Silo → Chain Conveyor → Bucket Elevator → Upper Silo
Therefore, they are often not competitors but complementary systems.
Feeding Product from a Big Bag to a Bucket Elevator
Example process:
Big Bag Discharge → Hopper → Screw/Star Feeder → Bucket Elevator → Silo
This system can be used for filling high-level silos.
However, the Big Bag discharge capacity must be compatible with the bucket elevator’s capacity.
An internal link to the Big Bag Discharge Systems guide should be provided from this section.
Silo Filling with a Bucket Elevator
One of the most common applications of bucket elevators is silo filling.
Process:
Product Inlet → Bucket Elevator → Top Distributor → Silo
can be designed in this manner.
If there are multiple silos at the upper level, the following can be used:
- chain conveyor,
- diverter,
- distributor
.
Use of Elevators with Powdery Products
When powdery products are transported through an elevator, air and dust movement may occur within the system.
For this reason,
- body sealing,
- suction points,
- the filter system,
- and connection gaskets
are important.
If necessary, the bucket elevator should be designed in conjunction with a dust collection system.
Integration of the Bucket Elevator with a Jet Filter
Dust may mix with the air during product discharge at the top outlet of the bucket elevator.
Dust in this area can be controlled using:
- a local jet filter,
- or a central dust collection line.
The filter flow rate should not be selected arbitrarily.
Product flow rate and air movement must be evaluated together.
What Factors Affect the Energy Consumption of a Bucket Elevator?
The main factors affecting motor power are:
- hourly capacity,
- vertical height,
- product weight,
- moving equipment weight,
- friction,
- system efficiency.
From a simple physical perspective, the theoretical power required to transport the product vertically is related to the following formula:
P = m × g × h / t
However,
However, when determining the actual motor power, the following must also be taken into account:
- mechanical losses,
- starting torque,
- service factor,
- and moving equipment weight
.
Example Theoretical Power Calculation
For illustrative purposes only:
Capacity: 20,000 kg/h
Vertical height: 20 m
Mass flow rate:
20,000 / 3,600 = 5.56 kg/s
Theoretical power required solely to lift the product:
5.56 × 9.81 × 20 ≈ 1,091 W
Approximately:
1.1 kW
is obtained.
However, the actual elevator motor is certainly not selected based solely on this value.
The system must be calculated in conjunction with:
- mechanical friction,
- belt/chain weight,
- bucket weight,
- start-up conditions,
- a fully loaded start-up scenario,
- and efficiency
.
The purpose of this example is to demonstrate that energy calculations are not based solely on capacity.
10 Common Mistakes in Bucket Elevator Selection
1. Selecting based solely on capacity in metric tons per hour
Product density and particle characteristics must also be known.
2. Assuming the bucket volume is the actual capacity
Buckets are generally not completely full.
3. Selecting a chain or belt system without conducting a product analysis
Temperature and wear can affect this decision.
4. Failing to account for product breakage
High-speed systems can damage delicate products.
5. Leaving the bottom feed uncontrolled
Overfeeding can cause the elevator to become clogged.
6. Incorrectly designing the top discharge geometry
Product may spill back into the lower housing.
7. Failing to assess the risk of foreign objects
Chains and buckets may be damaged.
8. Failing to consider maintenance access
Access to the lower and upper sections must be provided.
9. Neglecting the tensioning system
This can shorten the life of the chain or belt.
10. Postponing dust control considerations
For dusty products, filters and extraction systems must be designed from the outset.
Bucket Elevator Malfunctions and Quick Diagnosis Chart
Problem Possible Cause
Low capacity Bucket not filling / insufficient feed
Elevator jamming Excessive feed / product buildup
Chain slamming Tension / elongation
Belt slipping Low tension / overload
Product falls back Incorrect discharge geometry
Bucket breaks Foreign object / overload
Housing wears out Abrasive product / incorrect liner
High motor current Mechanical jam / excess product
Increased vibration Alignment / bearing / chain problem
Dust escapes Housing leak / insufficient suction
What Information Is Required for a Bucket Elevator Quote?
The following information must be provided prior to a technical quote:
Technical Data Description
Product name Raw material to be conveyed
Capacity kg/h or t/h
Bulk density kg/m³
Particle size mm
Maximum particle size mm
Vertical height meters
Product temperature °C
Moisture %
Abrasiveness: Low / medium / high
Brittleness: Yes / no
Feeding method: Continuous / batch
Inlet equipment: Screw conveyor, hopper, etc.
Outlet equipment: Silo, conveyor, etc.
Operating time: hours/day
Material preference: Carbon steel / stainless steel, etc.
Environmental conditions: Indoor / outdoor
Dust risk: Filtration required
Bucket Elevator Selection Checklist
All of the following questions must be answered before making a technical selection:
- What is the product’s form?
- What is the bulk density?
- What is the maximum particle size in mm?
- Is the product brittle?
- Is the product abrasive?
- What is the product temperature?
- What is the target capacity in metric tons per hour?
- What is the vertical height in meters?
- Will it operate continuously or in batches?
- Is a belt or chain more suitable?
- What bucket type should be used?
- Is dust collection required?
- Where will the product go at the top discharge?
- How will the bottom feed be controlled?
- Is there sufficient access for maintenance?
Frequently Asked Questions
What is a bucket elevator?
A bucket elevator is a mechanical conveying system that transports bulk materials, such as powders and granules, to great vertical heights using buckets.
What is a chain elevator?
A chain elevator is a type of bucket elevator in which the buckets are attached to a chain as the carrying element. It can offer advantages in heavy-duty and low-speed applications.
Which is better, a belt elevator or a chain elevator?
There is no single correct answer. The choice should be made based on product temperature, density, capacity, wear, and speed requirements.
How is the capacity of a bucket elevator calculated?
Bucket volume, fill ratio, bucket spacing, travel speed, and product bulk density are evaluated together.
Why does a bucket elevator get clogged?
Overfeeding, product buildup, improper discharge, sticky product, or foreign objects can cause clogging.
Where are chain elevators used?
They can be used for bulk materials that are heavy, abrasive, high-temperature, or require low-speed transport.
How are bucket elevator buckets selected?
In addition to bucket volume, product density, particle size, abrasiveness, temperature, and brittleness must be taken into account.
What is the maximum height for a bucket elevator?
There is no single standard maximum value. Engineering calculations are performed based on capacity, mechanical loads, the conveyor system, the chain/belt, and the facility geometry.
Is an elevator or pneumatic conveying more economical?
An elevator may be advantageous if only high-capacity vertical conveying is required. In complex horizontal-vertical routes, a pneumatic system may offer greater flexibility. Total investment and operating costs should be compared.
Does the product break in a bucket elevator?
Incorrect speed, bucket geometry, or discharge method can cause damage to fragile products. Low-speed, continuous-discharge designs may offer advantages for certain products.
Conclusion: How to Choose the Right Elevator for High-Vertical Conveyance?
Bucket elevators are an extremely robust mechanical conveying solution for transporting bulk raw materials over great vertical distances.
However, the system’s success does not depend solely on the elevator height.
For the correct design:
product characteristics + capacity + vertical height + bucket geometry + speed + conveying system + feeding + discharge
must be evaluated together.
While belt elevators offer advantages in many high-speed, high-capacity applications, chain elevator systems may be more suitable for processes requiring heavy-duty, high-temperature, and low-speed conveying.
Especially with abrasive or fragile products, it is not just the capacity target that matters;
- equipment lifespan,
- product quality,
- maintenance costs,
- and energy consumption
must all be evaluated together.
In conclusion, the right elevator is not
the one with the largest motor or the fastest system, but rather the system that transports the product to the required height at the desired capacity and with sustainable operating costs.
Let’s Choose the Right Bucket or Chain Elevator for Your Project Together
Share the name of the product to be conveyed, its bulk density, particle size, hourly capacity, and vertical conveying height with the MASTRON Process engineering team.
For your application, let’s evaluate the following alternatives throughout the entire process:
- belt-type bucket elevator,
- chain elevator,
- screw conveyor,
- chain conveyor,
- pneumatic conveying.
Let’s evaluate these alternatives together.