Top 10 common service calls on overhead cranes and how to prevent them

By Jonathan Cadotte
Service manager at Premium Industrial Group inc.

A plant without production downtime! Machines without service calls! The ideal world for team leaders and managers! Too good to be true? At present, yes.

Therefore, if you have your team’s productivity at heart, you may feel stressed when a problem occurs on a machine. Imagine your production paralyzed just before a crucial delivery!

Will you be able to restart production quickly, or will it be a long and arduous shutdown of a section of your plant? Will you have to call in a technician who may be the bearer of costly bad news?

Yes, an overhead crane operator announcing his concern about a noise, a strange behavior or a malfunction can be a source of worry.

If you’re on this page, you don’t have any critical service calls in progress at the moment, but you’d like to prevent them as much as possible. Good news then! That’s what this article is all about.

From a small team of a few technicians 15 years ago, Premium now has around 20 full-time technicians on the road, plus a team of supervisors and technical support. In this article, not only will you discover the 10 most common service calls on an overhead crane, but, more importantly, you’ll learn how to prevent each one to ensure the best productivity.

Service call 1 : Remote control problem

What could be more annoying than a production stoppage due to a simple remote control issue? And the causes can be many…

1. Normal wear and tear
2. Crushing damage, caused by a forklift truck for example
3. Lost remote control
4. Frequent chocs. For example, if often dropped on the floor
5. Parts melted by excessive heat, e.g. from a steel plate heated nearby
6. Discharged battery

Prevention solutions : The spare remote control

In this case, the best prevention is simple: always have a spare remote control ready for use. Don’t wait for your remote control to break before ordering another one. Even though your supplier may have some in stock, a stockout or delivery delay can slow down your production.

Let’s move on to another electrical part that can cause frequent service calls.

Service call 2 : Faulty contactor

Contactors are essential for operating the movements of your lifting equipment. That’s why they can cause service calls. What are the signs and causes of this type of call?

Signs of a faulty contactor :

1. A rumbling engine
2. A motion that behaves strangely. Here are a few examples :
• Equipment responds well at low speed but moves in the opposite direction when shifted to high speed.
• Equipment doesn’t move when a function is pressed.
• Equipment doesn’t stop when the button is released.
  
  

What causes a faulty contactor?

Contactors, like all other parts, wear out over time. But in addition to normal wear and tear, premature wear and tear can be caused by repeated stop/start operations, commonly known as “jog” (function pressed repeatedly).

So what can you do to reduce these calls?

Prevention solutions : Training and preventive replacement

It’s true that these calls are more difficult to prevent, but there are solutions.

To avoir premature wear and tear caused by frequent stops and starts, the best preventive measure is to ensure that operators are properly trained in the use of overhead cranes.

Also, if the equipment is crucial to your production, it can be advantageous to replace certain contactors in advance, by analyzing the history of past replacements. Although it may seem costly, this preventive replacement often avoids much more costly breakdowns. Another possibility is to replace the contactor system with variable frequency drives (applicable for horizontal movements).

Let’s move on to a crucial piece of equipment: the hoisting cable.

Service call 3 : Damaged hoisting cable

The hoisting cable is an essential component of the hoist, and a critical element when lifting a heavy load. Occasionally, snagging, sudden overloading (“shock load”), side pulling or loss of rope tension (“slack rope”) can damage the hoisting cable and require replacement.

For more details on this situation, see The hoisting cable: Carrying a heavy load

 

Prevention solutions : Training and risk analysis

Most of the time, cable damage is caused by incorrect handling by the operator. The solution: train operators to move loads properly in their environment.

When several pieces of equipment can cross or interfere with each other, it’s important to carry out a risk analysis. For example, the presence of jib cranes on the ground or overhead cranes at different heights. The result of this analysis will help reduce the risk of accidents.

But what if the overhead crane won’t restart?

Service call 4 – Overhead crane failure

This happens mainly when the operator returns to work, at the start of the day or after lunch break. We attempt to start operations, but the crane no longer responds.

In general, crane breakdowns have a relatively simple cause. For example, someone may have padlocked the equipment without informing the next operator. Or it could be an emergency stop that’s stuck.

But in some cases, the source of the problem seems inexplicable and requires a few interventions before a solution can be found. This is the case, for example, when a fuse has blown. Sometimes, it’s just poor handling by the user. But in other cases, a more thorough investigation by the technician will be necessary.

Prevention solutions : Communication

Preventing this kind of stoppage is more difficult. Training can play a small role. Alternatively, perhaps better communication between the various parties involved can help reduce the number of such calls. The concept of “return on experience” (REX) may be useful here.

Another case: braking!

Service call 5 – Inadequate braking

This type of call occurs when the operator believes the overhead crane has a braking problem.

Sometimes, it’s the operator who deems the stop too slow. In fact, the stopping delay of an overhead crane should be 10% of its speed. For example, if the crane is travelling at 20 meters per minute, it should stop within 2 meters when the travel button is released (at maximum capacity).

In other cases, the hoist may not brake during ascent and descent, causing the load to descend slowly but involuntarily (the hoist is said to “not hold its load“). This situation is the result of a worn-out brake.

Prevention solutions : Inspection

In the case of a load brake, the problem is prevented by periodic inspections according to the class of use. This allows us to keep a close eye on brake wear.

For the travel brake, it’s more a question of working methods. If your operator finds that the load doesn’t stop quickly enough, you need to analyze the work process and look at the possibilities. But it’s also important to bear in mind that braking too abruptly can cause the load to sway dangerously.

Let’s move on to mysterious noise.

Service call 6 – Abnormal noise

Typically, the operator reports an abnormal noise that seems to be coming from the drum on the wire rope hoist or the drive mechanism on the chain hoist. You may also hear “my overhead crane is creaking” or “I can hear a vibration”, which can be a cause for concern.

Most of the time, it’s a problem of lubrication of the cable guide or the pocket wheel (the wheel where the chain runs). This is particularly the case in dusty working environments, such as sandblasting chambers. In certain circumstances, more frequent lubrication is required.

Prevention solutions : Maintenance during inspection

Periodic inspection remains the best form of prevention, as it includes lubrication, which should be based on the needs of the industry. Some environments require different lubricants and different lubrication frequencies.

Let’s now talk about collector shoe problems.

Service call 7 – Collector shoes out of position

The collector shoes are blade-like arms that slide along the conductor bars to allow electrification throughout the travel. When these shoes move partially or completely out of position, the overhead crane stops.

This is a fairly common occurrence, especially in outdoor environments in winter. Ice buildup can throw the shoe out of alignment. In other cases, bars in poor condition are the cause. Or the wear on the blades makes them sharp or prickly, and they pull the shoe out of place when they dig into the junction between the conductor bars.

Prevention solutions : Weather protection… and inspection

As far as winter ice is concerned, conductor bars can be covered to protect them from bad weather, such as freezing rain. But otherwise, inspection will help detect wear and tear on the bars or blades before it causes a shutdown and a service call.

Let’s now take a look at the human causes of service calls.

Service call 8 – Operator issue

Although it’s delicate, we have to admit: service calls are sometimes caused by the operator himself. After all, nobody’s perfect!

Here are a few examples of operator-induced service calls :

1. A hoisting cable needs replacement due to improper handling by the operator
2. An operator reports slow braking, even if normal
3. The lifting hook latch has been removed by the operator
4. Poor slinging practice

Prevention solutions: Training, clarity and support

First of all, it’s important to mention that most workers want to do the right thing. Often, it’s just a matter of good coaching. The starting point is, of course, proper training. You also need to implement the right work methods and ensure that the employee understands the task he or she was assigned.

That said, it is sometimes necessary to combat resistance to change by providing the worker with the right guidance. We can, for example, make them aware of the importance of good practices by clearly explaining the consequences of not applying them, especially when there is a risk of injury or breakage.

And what if the overhead crane moves unevenly?

Service call 9 – Misaligned overhead crane movement

We’re talking here about an overhead crane that moves faster on one side of the crane runway than on the other.

This problem is most often caused by a lack of maintenance. The brake is too worn on one side, or a braking control part is damaged. In some cases, the motor itself is faulty. It can also be an electrical or mechanical failure. For example, a wheel may have worn down more quickly due to friction.

Prevention solutions : Brake wear during inspection

An inspection will often reveal any anomalies, for examples, by checking that brake wear is acceptable and adjusting them if necessary. However, no one is immune to breakage. That’s why it’s important to ensure that the equipment in place complies with CSA standards. Why is that? Because the availability of parts for equipment that doesn’t meet Canadian standards will be affected, making your overhead crane’s restart delay uncertain.

Service call 10 – Inspection required by the CNESST

The Commission des normes de l’équité, de la santé et de la sécurité au travail is increasingly active across Quebec to ensure that workers are safe in their workplace. An inspector can visit your industry at any time for a safety audit.

If an inspector discovers safety problems with your installation, he or she may ask to consult your logbook to verify the maintenance you’ve carried out on your equipment (for more details on what a logbook is, see the article Compliance of Lifting and Handling Equipment). A derogation may be granted to you, which will give you a relatively short time to conduct an inspection or load test.

In such cases, an inspection that should be a planned event becomes an urgent necessity. It may even generate additional costs for you. For example, since your deadline will be short, your service provider may have commitments that prevent them from serving you during their normal working hours.

What can you do to avoid this situation, which could disrupt all your planning?

Prevention solutions : Planned inspections

The solution here is simple: Organize scheduled periodic inspections according to the class of use. High standards and potential accidents require equipment owners not to leave lifting equipment maintenance to chance.

The winning trio : Inspection – Maintenance – Training

Obviously, the previous list is not exhaustive. But it does highlight some common service calls, their usual causes, and above all, the preventive solutions that can help you keep such calls to a minimum.

Although you can’t prevent all service calls, reducing them as much as possible is sure to boost your plant’s productivity.

So, what actions can you reasonably take in view of what we’ve just analyzed? You’ve probably noticed that some of the solutions have been repeated throughout these 10 frequent service calls! Here, then, are the key actions that form the basis of prevention. We also suggest a few related articles to help you learn more about each of these elements:

You are determine to fight service calls! Excellent decision! But where do you start? The first step is the inspection, because the inspection report will give you an overview of the condition of your overhead cranes. It will enable you to establish your strategy for winning the battle. That’s why we recommend that you consult our page on inspections to learn about the different types of inspection and their frequency.

Premium Industrial Group specializes in overhead cranes and has been providing overhead cane inspection and repair services since the very beginning. We’re happy to contribute to our customers’ prevention plan. Take control of your productivity by planning your next periodic inspections now. You can fill in the form at the bottom of the page, and we’ll be happy to offer you our best advice.