A flat-top crane is a tower crane in which the jib and counter-jib connect directly to the slewing unit on top of the mast, with no tall structure above them. In Potain (Manitowoc) cranes, the MDT series is the flat-top range, and the MD series covers cranes with a tower head. RMA’s rental fleet, which stands at 190 tower cranes as of 2026, includes cranes from both series. In this article we explain the differences and help you understand when a flat-top is the right choice for your site.
On a crane with a tower head, sometimes called a “hammerhead”, a vertical structure rises above the jib. Tie bars or cables run from it to carry the jib and the counter-jib. A flat-top crane has no such structure: the jib itself is built to carry the loads, and the top of the crane is flat.
Both are static tower cranes, set on a chassis or on a base section, that can be raised and tied to the building, and are operated by a crane operator holding a valid certificate. The same safety requirements apply to both, including inspections by a certified inspector under the Safety at Work (Tower Cranes) Regulations, 1966. The main difference is the configuration of the upper part of the crane and its effect on planning the site.
On large sites, or on adjacent sites, several cranes sometimes work with overlapping work areas. For one jib to pass over or under another, a height difference must be kept between them. When the lower crane has no protruding tower head, the required height difference between the cranes can be smaller. That allows overlap to be planned at lower heights and with more flexibility. Even with a correct height difference, however, the hoist rope of the higher crane descends through the work area of the lower crane, so a height difference alone does not prevent a collision. On a site with overlap, the guidelines of the Occupational Safety and Health Administration refer to integrated slewing limit switches or an anti-collision system, and the certified inspector checks that they exist and work properly. It is therefore worth including an anti-collision system at the planning stage. RMA installs advanced anti-collision systems that have been tested and approved by the Standards Institution of Israel and the Ministry of Communications. Details are on the technological innovations and safety page.
Some sites have a limit on the overall height of the crane, for example near airports and helicopter landing sites, or because of other planning restrictions. On a flat-top crane the top of the crane is closer to the height of the jib, so more of the permitted height can be used for actual work. The restrictions themselves are set by the competent authorities and must be checked for each site separately.
Because there is no tower head and no tie bars, erecting a flat-top jib is usually simpler. Even so, the complexity of erection also depends on the model, the jib length and site access conditions.
A flat-top is not the right answer for every site. An MD crane with a tower head may suit better when:
The right comparison is between specific models, using the manufacturer’s load charts, and not between “flat-top” and “MD” in general.
| Criterion | Flat-top (Potain MDT) | Tower head (Potain MD) |
|---|---|---|
| Structure above the jib | No protruding tower head | Tower head with tie bars |
| Overall height above the jib | Lower | Higher |
| Planning overlap between cranes | Usually a smaller height difference is required | Usually a larger height difference is required |
| Sites with a height limit | Particularly suitable | Check against the overall height |
| Choosing a model | From the manufacturer’s data sheet | From the manufacturer’s data sheet |
Choosing a crane starts from the needs of the site, and only then moves on to the crane type. The main steps:
Choosing a crane larger than needed raises the cost of the project, and choosing one that is too small limits the work. It is therefore worth comparing against the load charts at the planning stage. The manufacturer’s data sheets are available on the technical information page, and the models available for rent are in the crane rental catalogue. RMA’s team of 60 staff, technicians and engineers, including engineers and consultants, can help with the choice. Call 08-9202882 or send a WhatsApp message.
A flat-top crane is a tower crane with no protruding tower head above the jib. The jib and counter-jib connect directly to the slewing unit on top of the mast, so the top of the crane is flat.
The MDT series is Potain’s flat-top range. The MD series covers cranes with a tower head, from which tie bars run to the jib and the counter-jib.
Because it has no protruding tower head, the height difference required between overlapping cranes can be smaller, which makes overlap easier to plan.
No. When there is no height limit and no overlap, an MD crane may suit just as well or better. The choice is made from the load charts of specific models.
The manufacturer’s data sheets are available on the technical information page of the RMA website, and the models available for rent can be seen in the crane rental catalogue.
Yes. Sites with overlapping cranes need collision-prevention measures, such as integrated slewing limit switches or an anti-collision system, and the certified inspector checks them. RMA installs advanced anti-collision systems that have been tested and approved by the Standards Institution of Israel and the Ministry of Communications.
The information in this article is general only and is not engineering, safety or legal advice. Before any decision, follow the manufacturer’s instructions and the applicable law, and consult certified professionals.
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