Demag Crane Spec Checklist: Six Checks Before You Order
If a request says 'Demag crane spare motor' without a serial number or component reference, stop there. I learned this the slow way. Demag cranes are built to last, which is why many old units are still running. The long service life has a downside: lots of machines have been modified, fitted with different hoists or motors, or repainted over their original nameplates. If you order from memory, you are gambling with someone else's time and money.
I have handled Demag crane component orders for about nine years. In that time I documented 11 specification mistakes that added up to roughly $24,000 in reorders, extra freight, and downtime. The worst one, in 2019, happened because I ordered a replacement hoist motor using only the crane model. The quotation listed a Mannesmann Demag electric motor. The price looked fair and the name looked right. The frame and power rating matched. The brake coil voltage did not match the existing control panel, which only became clear during installation. We paid for the motor, paid for a rush order, and still lost four days of crane availability.
This is the checklist I use now before purchase orders go out. It is for anyone who buys crane parts, replaces motors, works as a terrain crane distributor, or prepares mobile crane specifications for a rental fleet. It is also worth reading if you need to issue a city crane specification guide for tight urban sites.
The six checks I use before an order
- Photograph the nameplate.
- Separate crane data from component data.
- Verify duty, not just physical size.
- Check the electrical details.
- Define the whole crane configuration.
- Confirm the specification in writing.
Check 1: Photograph the nameplate
Before you write an email, walk over to the crane and take photos of every plate you can find. Most units have more than one: a main crane plate, a hoist plate, a motor plate, maybe a control panel plate. One plate will be easy to read. Another will be in a spot that needs a ladder or a flashlight. Take the photo anyway.
If the plate is painted over, ask maintenance to clean it carefully enough to read. In 2021, I spent two days trying to identify a hoist because someone had painted over the identification during a refurbishment. A legible photo at the start would have saved most of that time.
A photo is not the full specification, but it gives the supplier something concrete. It also stops us from typing the same incorrect description into three different quotes.
Check 2: Separate crane data from component data
The word Demag appears on cranes and on components, but those are different pieces of information. The crane plate tells you how the machine was originally built. The motor plate tells you what motor is installed today. They are not always from the same stage in the machine's life.
An older Demag crane may still have its original hoist. Or it may have had the hoist replaced during a major service. The motor may have been swapped for a newer unit because the original failed. None of that means the crane is unreliable. It means the spare parts request should be based on the actual component data, not on the crane model.
The same is true for the well-known name Mannesmann Demag electric motors. That name identifies a family of motors, not one motor model. When someone asks me for 'a Mannesmann Demag electric motor,' I ask them which motor. Type code, article number, serial number, voltage, speed: all of that narrows the search. The brand alone is not enough.
Check 3: Verify duty, not just dimensions
Two motors can look almost identical and still be rated for completely different work. Same shaft height, same power, same size. But one may be intended for intermittent travel motion while another is designed for a hoist with frequent starts and stops. If you replace the wrong one, you might create an overheating problem instead of solving one.
This is not only about motors. The same thinking applies to cranes. Lifting capacity is only one spec. Duty, load cycles, span, and intended application all affect the right choice. A crane that is perfect for occasional maintenance work may be badly oversold for two-shift production use.
Check 4: Check the electrical details
Most people include voltage and power in a motor request. That is a start, but it is only part of the picture. Brake release voltage, brake coil data, thermal protection, speed feedback, and control voltage are equally important. If those details do not match the control panel, the motor may spin up fine on a test bench and still not work inside your crane.
My 2019 mistake was exactly that. The motor was correct in frame and rating. The brake voltage was not compatible with the rectifier in the existing panel. Nobody caught it before shipment because I had not provided the control panel details. The supplier could only work with what I sent.
Now I ask for a copy of the nameplate photo and the control panel data if it is available. If the supplier needs two extra days to check compatibility, that is better than paying for a motor that cannot be installed.
Check 5: Define the whole crane configuration
Mobile crane specifications are not just max capacity. They only make sense when the configuration is included: boom length, jib, counterweight, outrigger setting, and machine serial number. The same model can be ordered with different options, and those options change what the crane can lift at a given radius.
If you are a terrain crane distributor, this matters on every used unit you list. A load chart from another machine in the same model family is not automatically valid for the machine you are selling. The configuration has to match the actual steel, attachments, and counterweight installed on the unit.
It also matters if someone asks you to produce a city crane specification guide. Cities usually have strict limits on width, height, weight, and turning radius. Those numbers should come from the machine in front of you, not from a brochure scan of a different variant.
Check 6: Confirm the specification in writing
After the third incorrect quote in Q1 2024, I made a rule for our team: no purchase order until the supplier confirms the specification in writing. The email must include the machine serial number, the component model or part number, and the technical details that matter for the application.
Written confirmation sounds like extra admin work. It has saved us more time than it costs. In the past 18 months, we caught 17 potential order errors before payment. Most were small. One was a motor with the wrong brake voltage, sent by a supplier who had missed the detail in a phone call. Because we had the email, we caught it before the order went through.
If a supplier says 'do not worry, we know what you need,' I still want it in writing. This is not about distrust. It is about keeping the same information in front of both sides from the first quote to the final delivery.
Red flags I do not ignore anymore
- 'Same as the last order' with no purchase order number.
- 'Fits Demag' with no component type or serial number.
- A mobile crane load chart that came from a different machine.
- A city crane dimension sheet that cannot be traced to the actual unit.
- Any request that starts with 'I think it is...'
No checklist catches every problem. It will not replace a qualified engineer's review, a load chart check, or a proper site survey. But it will stop the ordinary specification mistakes that quietly eat budgets and schedules.
The point is not to make ordering slower. It is to make every order conversation shorter and more useful. When the correct information goes out, the correct part comes back faster. That is worth more than the few minutes it takes to walk to the machine, take a photo, and write down what is actually there.