Liebherr presents the new LTM 1750-9.1 at Customer Open Days

On 13 and 14 June, at the production plant at Ehingen, Liebherr presented the new LTM 1750-9.1 all-terrain crane to more than 2,000 customers from all over the world. The 750-tonne mobile crane complements the Liebherr range between the highly successful models LTM 1500-8.1 and LTM 11200-9.1. One particular feature of the new nine-axle unit is the fact that the complete telescopic boom can be carried during travel on public roads. To help make operation even more economical worldwide, account was taken in the design concept of the LTM 1750-9.1 of the very widely differing transport weights and axle load variations. Another point of focus in the design, too, was particularly short set-up times.

Wide operational range with powerful boom systems
A very broad range of equipment options means that the new LTM 1750-9.1 has a particularly wide operational spectrum. With the 52 metre long telescopic boom, the telescopic boom Y-guying system, and a whole array of different lattice jibs, the crane has a large number of different boom systems available, and can achieve heights under hook of up to 154 metres and outreaches of up to 112 metres. The luffing fly jib can be extended in 3.5 metre increments, out to 91 metres. The luffing of the fixed lattice jib, up to 62 metres long, can, as an option, be carried out hydraulically, which means that the jib can also be adjusted under load. A special auxiliary jib, with a load capacity of 56 tonnes, is also available for operation on the telescopic boom, at the fixed jib, and at the luffing jib. There are individual load capacity tables for this jib in the LICCON load moment limiting system.

The tried and trusted telescopic boom Y-guying system provides for an enormous increase in load capacity on the new LTM 1750-9.1 as well, in particular with long boom systems, due to the lateral stability being significantly improved. During the guying procedure, the cables are drawn by tensioning cylinders on both sides to precisely the same length, which means that the boom is held in a statically optimum straight position.

Variable axle loads
The LTM 1750-9.1 travels with its 52-metre telescopic boom, the front supports, an auxiliary support at the rear, and a complete hoist gear, at a gross weight of 108 tonnes with an axle load of 12 tonnes. Some countries, however, only allow for a gross weight of 99 tonnes with an axle load of 11 tonnes. These limitations can still be respected by the new 750-tonner if all the supports are taken off. As an alternative, the telescopic boom can be removed. And in order for the LTM 1750-9.1 to be driven on public roads even in countries with even more restrictive regulations, the new crane can be dismantled to reduce gross weights of less than 40 tonnes, in order to respect the maximum axle loads required in each case.

Rapid set-up and innovative drive concept
When the LTM 1750-9.1 arrives on site with its telescopic boom and the front supports, it can fit the rear supports itself, without the need for an auxiliary crane, with the aid of the optional additional support on the rear of the vehicle. In this situation, the crane set-up functions are powered by the engine in the carrier. The drive system for the crane superstructure, consisting of the engine and the hydraulics system, together with an integrated ballasting device, is transported to the site separately, fitted to the crane by self-assembly, and connected by quick-action couplings. All the crane functions for working operations are powered by the superstructure engine. In the event of a problem with the superstructure drive, all the crane functions can then be driven by the engine in the chassis, simply by rearranging the plugging of just three electrical connections, rapidly and easily. This innovation has been introduced for the first time on the new LTM 1750-9.1.

Economy combined with comfort
Powerful travel drive in the carrier of the LTM 1750-9.1 is ensured by an eight-cylinder Liebherr Diesel engine, rated at 500 kW / 680 HP and with a torque of 3,000 Nm. The power is transferred to the crane axles by means of the 12-speed ZF-TC-Tronic transmission. A torque converter is provided for start-up and fine sensitivity manoeuvring. The intarder serves as the continuous service brake, a hydraulic brake integrated into the transmission system and free of any wear. As with all current AT-cranes from Liebherr, the LTM 1750-9.1 is equipped with compressed-air disk brakes, which ensure safe and economical travel operation.

The four rear axles of the nine-axle chassis of the new 750-tonner are actively steered electro-hydraulically and speed-dependent, which increases the manoeuvrability of the vehicle and substantially reduces tyre wear. In crab steering mode, all six axles are steered, which means there is no longer any need for axles to be raised. Five steering programs can be easily and conveniently selected at the push of a button.

The Liebherr four-cylinder in-line engine in the crane superstructure delivers 270 kW / 367 HP and a torque of 1,720 Nm. The crane drive, which is provided with power steering and power regulation, is a Diesel hydraulic system with five axial piston adjustment pumps. The winches and the slewing gear are operated in a closed circuit for maximum fine sensitivity. Four working movements are possible simultaneously.