Overhead cranes which move 30 ton ladles of molten metal present a particular challenge to the maintenance engineer. They are critical machines and are usually in continuous operation, during which the motors and gearboxes are inaccessible. The environment is dirty and very hot. Unplanned breakdowns can be very costly, and even more serious is the safety risk of a catastrophic failure.
The Motornostix system has been found to be a cost-effective and appropriate means of condition monitoring of overhead cranes. Once installed, the system continuously takes measurements of vibration, temperature, current and other trends of the cranes' components periodically (usually every five minutes), and also takes longer data samples that can be subjected to vibration analysis at least daily, or if specified trend levels are breached.
There is no need for anyone to have to climb to dangerous positions to collect data. The Motornostix system is self-contained on the crane, and keeps sending its data to the Motornostix data centre where the data is processed automatically for alarm checking, This data is monitored by Motornostix analysts and is also available to authorized users via the Internet.
The system provides effective early warning of conditions that could lead to failure, information to make scheduled maintenance plans, and priority alerts to conditions that indicate safety risks (such as increased brake temperatures).
A Motornostix installation on a crane would typically monitor the following components with sensors covering all critical locations and measurables:
- Main hoist motor and gearbox
- Auxiliary hoist motor and gearbox
- Main hoist brakes
- Auxiliary hoist brakes
- Long travel motor and gearbox
- Cross travel motor and gearbox
Frequently encountered failure modes in overhead cranes which the Motornostix system is able to detect:
- Hoist brake failure
- Motor - gearbox alignment
- Coupling imbalance
- Motor/ gearbox loose foot
- Bearing surface wear
- Gear surface wear
- Looseness