Safety and Training | By STAHL CraneSystems | May 20, 2008
When transporting molten metals or hazardous materials such as acid or lye, strict regulations apply to ensure safety. For these types of lifting applications, German Industry Standard EN 14492-2 requires hoists to be designed in such a way that it is impossible for the load to fall, even if a component in the power flux should fail.
This requirement can be met in two ways: either by the redundant design of the hoist or by an emergency stop brake on the rope drum in conjunction with a redundant rope drive.
To meet these specifications, STAHL CraneSystems developed an off-standard hoist with twin drive concept (TDC) technology. By equipping a wire rope hoist with two synchronously controlled motor-gear assemblies and continuous drive monitoring, it provides the maximum possible safety when transporting molten metals with a weight of 5 to 40 tons. The complete redundancy of motor and gear always guarantees at least double gear and brake safety and the safety-relevant electronics are in category 3.
STAHL CraneSystems TDC hoist exceeds the demands of EN 14492-2, which requires a factor of 1.5. And, when the hoist is used for applications aside from molten metal transport, it can carry a 60% higher load.
Both motors of the TDC have brakes that are designed so that each is able to brake or hold the load on its own in an emergency. The brakes are synchronously controlled and function both as operating and as holding brakes. If a fault should occur (e.g. gear breakage), the load can be lowered with the two manual release brakes. “Retrieving the load” is thus no longer necessary.
Providing extra safety, a special condition monitoring system from STAHL CraneSystems monitors the speeds of both drives. If an overload is detected, a separate load monitor automatically disconnects the motor. The robust system is fully enclosed and thus not susceptible to dust and damp.
The TDC is just another example of STAHL CraneSystems commitment to developing safe lifting technology to help meet strict safety regulations around the world.
The 35 winch type SHWF with a wire rope hoist type SH as auxiliary hoist in the foreground.
As a leading manufacturer of hoisting technology and crane components, STAHL CraneSystems is comprised of individuals with unique and in-depth industry experience. Articles authored by STAHL CraneSystems belong to a collection of blogs written by product and application experts throughout the organization.