The electro-hydraulic disc brakes in the DX series from RINGSPANN have been re-engineered and are proving to be a trendsetter in the holding and emergency stop systems in the hoists of heavy-duty and container cranes. Designed for a high number of switching cycles on fast-rotating discs, and equipped with new angle levers and energy-efficient electrohydraulic thrusters, these innovative industrial brakes have significant added value – both in the design of the hoists and in their operation and maintenance.
Business developer for brakes at RINGSPANN, Martin Ohle says that important reasons for the high acceptance of these electrohydraulic brakes in the market is that they are assembly-friendly, user-friendly and service-friendly.
There are three factors that make these disc brakes an innovative solution: the substitution of numerous cast components with components made of flame-cut steel, the redesign of the angle lever and the use of a new type of electrohydraulic thruster. The compact dimensions of the new brakes are also striking. “Thanks to their compact design and the mounting dimensions of the base plate, they can be easily integrated into existing environments and can replace other models without modifications,” Ohle explains.
The steel design of the brake lever alone results in a major advantage. The brake is slimmer, it has a low unit price and the expense of maintenance, servicing and general overhaul is significantly reduced. The new design of the angle lever also has significant advantages. Ohler continues: “As a functional connection between the electrohydraulic thruster, brake spring and brake levers, the angle lever must absorb both bending and torsional forces. However, to ensure that these forces do not have a negative effect on the brake levers and bushings, we have recalculated the angle lever and designed it to have the same high torsional rigidity as a traditional cast iron solution. In addition, the new angle lever only has a few parts, which is why it is easy to install and replace.”
Designed for fast closing times
RINGSPANN has also had great success with the new electrohydraulic thrusters in its portfolio. They are tailor-made for use in demanding crane technology applications such as main hoists and trolleys, generate lifting forces of up to 8 kN, with very short closing times of <80 ms. They use a gear pump to generate pressure and the layout is analogue, so no circuit board is required. As before, they have a 3-phase connection. In addition, they impress with their high energy efficiency because when the brake is open, power consumption is very low, thanks to the pressureless circulation. The electrohydraulic thrusters contribute to the compact design of the brake and its easy maintenance should please every crane operator. As Ohler points out, wearing parts such as solenoids can be replaced while the thruster is installed in the brake.
Self-centring and automatic wear compensation
RINGSPANN also equipped the brakes with a functionality that makes it easier for the OEM designer to integrate the brake into the drive system, and makes life easier for crane operators and MRO personnel. For example, a standard, maintenance-free self-centring system ensures that the brake levers open synchronously, which means that the air gap on both sides of the brake disc always remains the same, even if the brake pads suffer wear and tear due to operation.
A different compensation mechanism ensures that the brake pads are always parallel when released. “The distance between the pads and the brake disc is decoupled from the V-position of the brake levers and is the same everywhere. This mechanism can be easily adjusted with adjusting screws,” explains Ohler. Another great advantage is that the wear compensation of the brake pads can be re-adjusted both manually and automatically. This is done by a maintenance-free freewheel mechanism. Since the wear compensation compensates for the increasing distance between the brake pad and the brake disc, the brake can always develop the same high clamping force.
These spring-operated service brakes close in the event of a power interruption and open by means of an electrohydraulic thruster. They are designed for a high number of switching cycles on high-speed discs with diameters of 355 to 1000 mm and provide clamping forces of up to 80 kN. At 230 mm and 280 mm, their brake centre heights are in line with the market standard. They are available in special versions for maritime, very cold and very warm environments, and also as explosion-proof models.
For more information contact Gerhard van der Westhuizen, RINGSPANN South Africa,
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