Bucket elevators: what are the failure modes of this asset?

Bucket elevators, also known as grain elevators due to their strong association with the agro-industrial sector, are assets found in various industrial segments, carrying out vertical, horizontal or inclined transportation of productive materials in order to dump them into chutes or pipes.

Main components of bucket elevators

Although there are certain particularities according to each type of elevator, fundamentally they are made up of the following elements:

Elevator head: this component located at the top of the asset is made up of the geared motor, transmission system, discharge chute and drive sprocket.

Discharge chute: this is the component responsible for guiding the contents poured into the buckets.

Central structure: this component connects the head and foot of the elevator and is made up of metal or wood sheets of a standard size.

Chain: this is the component on which the buckets are fixed, and which drives the movement of the drive sprocket.

Buckets: these receive the load for transportation and are fixed to the chain by means of deep or shallow cylindrical profiles, preserving the flexibility of the chain.

Infeed chute: the chute is the component that receives and guides the material into the buckets.

Inspection window: this is an access at the foot or head of the elevator for inspections and maintenance.

Tensioner: this component has the function of maintaining the tension in the chain required for its drive.

Elevator foot: located at the base of the asset, it consists of the turnbuckle, return sprocket and feed chute.

Types of bucket elevators

Bucket elevators can be categorized depending on their type of discharge, their position and the bucket’s coupling material. The main types of bucket elevators are:

Centrifugal discharge elevators

These are the most common types of bucket elevators. They are characterized by the spacing between the buckets, which are fed by a lower loading mouth. Discharge in this case takes place by the centrifugal force generated by the rotation of the upper pulley.

Continuous bucket elevators

In this type of elevator, the buckets have no spacing between them, so the material coming out of the loading mouth is immediately placed in the previous bucket.

Gravity discharge elevators

These types of elevators have spaced buckets which, via a device on the upper pulley, discharge the material by turning downwards. Gravity discharge elevators are generally used for handling pasty or glutinous material, which is why they are very popular in the food industry.

Positive discharge elevators

Similar to the positive discharge elevator, the buckets are spaced apart andhave a device on the upper pulley that turns them downwards. The main difference is the presence of two chains holding the side ends of each bucket.

Vertical/inclined/horizontal elevators

Variations in the positioning of the elevators vary according to the needs of the production flow. What changes in this case is the configuration of the buckets: vertical elevators use spaced buckets, in inclined elevators the buckets are continuous and, finally, in horizontal elevators the buckets are bascular.

Main faults in bucket elevators

Abnormal vibration levels

Excessive vibration is an important signal to watch out for in industrial assets. It can be indicative of a number of factors that pose a risk of serious failure. In the case of bucket elevators, abnormal vibration can originate from the following components:

• Loosening of the chain or straps;
• Chain or straps too tight;
• Loose, loose or rubbing buckets;
• Instability in the elevator foot;
• Misalignment in the elevator shafts;
• Presence of residue/dirt on components.

Bearings overheating

Abnormal heating of elevator components is also an indication of a possible fault, which can have serious consequences such as fires and explosions. Some possible causes of heating are: 

• Excess or lack of lubrication;
• Stretching of the chain or belt;
• Misalignment of bearings/shafts.

Problems unloading materials

When the elevator does not unload the materials correctly, production efficiency is compromised. The causes of this asset behavior can be associated with the following factors:

• Elevator operating at the wrong speed for the type of material being moved;
• Presence of air pockets when unloading in the ventilation compartment;
• Buckets unsuitable for the type of material being moved. 

The importance of continuous monitoring of bucket elevators

Bucket elevators are critical assets in industrial processes, and they represent a major safety gap if their inspection and maintenance is neglected. It is not uncommon for elevators to be the focus of fires and explosions. Incidents of this kind can occur due to a confluence of factors: the heating of some components, the presence of static electricity, dust and even flammable residues from the materials being transported can cause damage to the asset and put the safety of professionals at risk. 

To avoid such events, it is necessary to continuously monitor the components of bucket elevators. The temperature of bearings needs to be monitored frequently. Other components, such as the buckets, also need to be monitored to check for possible misalignments that could cause friction.

Vibration and temperature monitoring sensors

One way to avoid incidents and stoppages in bucket elevators is to use sensors to continuously monitor the elements that cause the faults mentioned above. 

The Dynamox solution has wireless vibration and temperature sensors. These devices continuously read asset health information and, when applied to bucket elevators, help maintenance teams to identify abnormal variations in vibration and temperature, making it possible to carry out a planned maintenance action without compromising the asset’s availability, as well as providing greater security for the process.

The sensors are IP66 / IP68 / IP69 and EX certified, the latter guaranteeing that the devices are not a source of ignition in potentially explosive atmospheres, as is the case in some environments where bucket elevators are in operation. 

To collect data from the sensors, the Gateway is used, which connects to the web platform via Ethernet or Wifi. It allows communication with the sensors, sending the information directly for analysis on the Dynamox Web Platform. There is no limit to the number of sensors per Gateway, making it possible for a single device to collect data from dozens or hundreds of sensors simultaneously. The solution also has an Ex Gateway for classified areas.

Want to increase the reliability and availability of bucket elevators? Discover the Dynamox Solution! Contact us to learn more.