Positive Rail Brake(Rail pressing device)

Overview

IHI has developed the crane safety device, the Positive Rail Brake (rail pressing device), to prevent runaway accidents that are frequently triggered by the abnormal weather conditions of recent years and equipment deterioration. This is a braking device that will safely stop a crane when an unforeseen situation causes the crane to start to run away. Our Positive Rail Brake is designed to be compact and flexibly accommodate installation position and installation quantity as needed, so it can be used for a range of crane models. This safety device will prevent major crane accidents caused by gusty winds.

Specifications

Pressing force: up to 65t, Static friction coefficient: μ=0.45
Dynamic friction coefficient: μ=0.2 (depending on conditions, 0.3)

Runaway accidents are occurring frequently in recent years with port gantry cranes and others. Runaway of cranes in operation because of gusty or stormy winds have caused grave and sometimes fatal accidents by crashing into adjacent machinery and derailing, collapsing, falling into the sea, or colliding with vessels.

Human life should always be the top priority for every company. It is crucial to create a safe environment that places human life first. An accident will cause not only substantial compensation fees and long-term shutdown, it will also trigger business downturn, the need to address shareholders and liability, and deterioration of the company image.

If the rail clamp fails to hold the rail due to rail abrasion, corrosion, or deformation, this may allow a runaway accident. And when the cause is gusty winds, the dynamic friction coefficient is small, so rail clamps alone cannot prevent accidents. Electric motor traveling brakes also lack capacity. This is why a new safety device is needed to handle runaway accidents.

The dynamic friction coefficient is small with rail clamps, so they cannot prevent runaway accidents. Also, the conventional spring-type rail brakes cannot control braking force, so the crane will suddenly brake and possibly sustain damage such as falling over. But with the Positive Rail Brake, braking force startup can be finely adjusted with hydraulic pressure, making it possible to stop safely.

With the Positive Rail Brake, both the rail brake itself and the hydraulic pressure unit are compact and lightweight, so it can be easily installed. Multiple units can be installed as needed, so it can accommodate a wide range of crane models.

Example of installation on a bridge-type unloader

IHI has verified braking performance not just with calculations, but by repeatedly testing the Positive Rail Brake using actual equipment.

＜Test conditions＞
(1) Travel speed: approx. 22m/min (2) Braking starts after traveling 10m (3) Traveling brake, rail clamp not functioning (4) Pressing force and hydraulic pressure function time gradually increased

The tests have proved that the Positive Rail Brake will stop movement at 1/6 the distance compared to inertia stopping.

Resistance (retention) performance test result

1) Static friction coefficient: μ=0.45

Braking performance test results (conducted 67 times)

1) Average stopping istance:449mm; stops at approx. 1/6 of the approx. 3000mm distance of inertia
2) Dynamic friction coefficient: μ=approx. 0.2 *Calculated from test results

Test results (stopping distance and braking distance)

When choosing the Positive Rail Brake, there is a need to consider pressing force, installation quantity, installation position, control system, and others.

Flow for selecting specification

＜Points of caution＞
(1) Installation position: There is need to install in the appropriate positions to properly use the crane’s weight. Please inquire in advance.
(2) We do not guarantee that it can stop under all conditions.