Fixed-end
The load limiter prevents loads that exceed the nominal capacity of cranes to be handled, taking into account the dynamic effects during normal operation.
- Electromechanical operation
- Electrical signals read by microswitch
- Electrical signals: 2
- Calibration sensitivity ±1%
- AISI 304 stainless steel and structure
- Protective treatments: Geomet 321, galvanization and nickel plating
- DU type dry shaft sliding bearing
- Gaskets of type OR
- DIN 40050 IP65 insulation class
- Operating temperature range -20° + 80°C
- Mechanical life 2×10^6 working cycles 2×1
- Max allowed power 15A 250V
- Electric cable supplied: 3X1 – 6X1.5 m. 2
DANFOSS, we block the risk by lifting safely!
All electromechanical load limiters are designed in compliance with legal directives and standards, with particular attention to workplace safety, and made for specific applications.
F.A.Q. - FIXED HEAD LOAD LIMITERS
It is a safety device that is applied to the rope of lifting systems to avoid lifting loads exceed the capacity of the system.
The load limiter slightly bends the rope between two pulleys and a central clamp anchored to a contrast spring. When the system lifts a weight, the rope tends to straighten, thus compressing the spring. As soon as the compression reaches the threshold set by calibration, a microswitch sends an electrical signal which blocks the system’s lifting motor.
Through a simple calculation: the nominal capacity of the system is divided by the number of rope falls (reeving). For example, in a system that has a capacity of 5 tons with 4 rope falls, the calibration must be set at 1,250 kg. In fact, this is the maximum force applicable on the rope.
Danfos limiters for fixed-end ropes are available in two lines: with one threshold; with two thresholds. Two-threshold models are useful when there is a need to detect the reaching of two different thresholds. For example, if you want to use the first threshold to detect when 90% of the system flow rate has been reached (and connect this threshold to a flashing light), and to use the second threshold to block the motor.
It is enough to know the nominal capacity of the hoist, the diameter of the rope and the number of rope falls (reeving). If you want to install a two-threshold limiter, you must inform the manufacturer at what value you want each threshold to be set.
Danfos limiters for fixed-end ropes cover, with various models, a range of rope diameters from 6mm to 32mm and capacities-per-rope from 250kg to 15,000kg. For measurements that do not fall within these values, customized solutions can be evaluated.
Normally yes. However, it is also possible to calibrate them during installation. In any case, a check and fine adjustment of the calibration at the time of installation is strongly recommended.
Danfos limiters stand out for their reliability and long-lasting calibration. It has been found that under normal conditions the calibration remains precise for years, therefore for a very long time. However, it is always recommended to check the calibration during periodic checks. If recalibration is needed, it can be carried out on site (as a second option, the limiter can be dismounted and sent to the company who will carry out the recalibration on the bench).
In all cases where installation on a stationary cable that does not move is possible. Typically on a rope with a fixed end but also on a rope without a fixed end, if the rope remains stationary near a compensation pulley.
Installation is simple and does not require interventions on the crane. Simply remove the central clamp, position the limiter near the fixed-end so that the rope rests in the two pulleys, mount the clamp by tightening the screws until it touches the base. It is then necessary to connect the cable with the electrical wires to the system control unit, following the instructions provided in the user manual. If the limiter is installed outdoors, it is advisable for the cable to come out from the bottom.
No maintenance operations are foreseen. The only recommended intervention is checking operation and calibration during periodic checks.
Danfos limiters are also designed to be used outdoor. In fact, all mechanical and electrical parts are closed and sealed (IP65). The external surfaces are Geomet® treated against corrosion due to rain and humidity, even in saline environments.
It is an added safety system, exclusive of Danfos limiters. This is an additional circuit with mechanical operation which guarantees the effectiveness of the limiter even if the microswitch is damaged or malfunctioning.
Except for any contingent problems, the delivery times of a limiter are a few days or a week at most. For supplies in large quantities, the timing is calculated each time.
