Crane Brakes Stop Downtime

Replacing the brakes on two 40-ton cranes has virtually eliminated ongoing maintenance issues.

If you can’t take the heat, stay out of the heat-exchange business. For Ryan Dorman, Facilities Manager at Ohmstede Ltd., Beaumont, TX (ohmstede.net), the key to beating the heat and keeping his cool was addressing the 40-ton elephant in the room—a 40-ton crane that required constant brake maintenance and adjustment. While the cost of parts and repairs was frustrating, the downtime was what really got his blood boiling. Re-routing projects to other bays or workarounds with smaller cranes were effective but challenging to orchestrate. Dorman found a permanent solution when he replaced the old crane brakes with MagnaShear units with Oil Shear technology from Force Control Industries, Fairfield, OH (forcecontrol.com).

Ohmstede builds and repairs heat exchangers in eight plants across the U.S. The company’s Sulphur, LA, plant covers 40 acres and features a number of 1-ton jib cranes, one 5-ton, two 20-ton, four 25-ton, and two 40-ton bridge cranes. The 40-ton cranes are 1993 Kone and 1974 Landel units. Of these nine bridge cranes, the 40-ton cranes are Ohmstede’s main production cranes, operating 12 hours a day, every day. When the 40-ton Kone bridge crane started to have issues, it quickly became a big problem for Dorman.

“Every time we bought a new brake for the Kone we would have to keep readjusting it. If we didn’t have it adjusted right, we’d have to replace the brake again within six months to a year for $3,000 to $4,000 each time,” Dorman explained. This caused the production plant financial woes and logistical and efficiency headaches. “If a crane goes down it becomes a hinderance because we can’t get past it. The Kone brake really cut into production every time it went down, and it was constantly going down.” This is because the Kone brake is in the same 640-ft bay runway as three other cranes, hindering them from moving north and south. This left Dorman with the unenviable task of shifting production all the way down to the other side of the facility to use the Landel crane while the Kone was down.

Neither solution was a great one for Dorman, especially when you consider that when the Kone went down, it was rarely temporary. “When the Kone went down, it was usually down for several days, if not a month, while we were waiting on parts.” Since the repairs had to be done at height, there was the inherent possibility of a safety issue with each repair or adjustment. In truly inconvenient fashion, the brake often failed in the evenings or on a weekend, making it difficult to get a service technician out to assess the situation.

Once Dorman had finally had enough and was done dealing with downtime, he looked for a better brake. Todd Grantham, a Sales Representative from Hoist & Crane Service Group, Jefferson, LA (hoistcrane.com), the local crane sales and service facility, investigated some options and suggested the Force Control brake. Force Control was offering a one-year warranty with the expectation of a longer life with no adjustments needed, all of which was music to Dorman’s ears.

The specified MSB6 brake was modified to include a splined shaft, rather than a keyway, to evenly distribute torque. Custom flange adapters were added to simplify the installation. Even with a steeper upfront cost, the new brake was installed on the Kone crane in 2012. More than ten years later, the results are still impressive for Dorman.

“Once we updated the Kone, it went so well it was pretty much set and forget it,” Dorman said. In fact, the Kone uptime improved so dramatically that Dorman’s team turned off the machine’s built-in control system. “The Kone used to have a control system that would shut down after so many cycles for you to check your brakes. After updating our Kone there was no need for this system anymore because our brake wouldn’t wear out.” The Kone control system wasn’t designed for a situation where the brakes didn’t need to be checked at such long intervals, so the Ohmstede team had to turn it off to avoid false alarms.

Ohmstede’s productivity gains came not only from Force Control but also from Hoist & Crane. “The original Kone brakes would just go out arbitrarily or come out of adjustment. You’d have to send a technician [whenever there was a failure], middle of the night or whatever, and you’d have to adjust it,” Grantham explained. Since the switchover it’s been a different story. “We change out the oil in the Force Control brake once a year and that’s it.”

How it works

The MagnaShear brake has essentially eliminated downtime.

Normal dry brakes use a disc or pad to engage the load. Without a good way to remove the heat caused from engagement between the disk and plate, this sacrificial material must absorb the heat. The extremely high temperatures will eventually degrade the friction material. As the friction surface wears away and begins to glaze, the spring force is also reduced, causing torque fade. This results in positioning errors that typically require adjusting or replacing the friction surface.

Oil-shear technology plays a major role in ensuring that the cranes in the plant operate continuously. A film of automatic-transmission fluid flows between the friction surfaces. As the brake is engaged, the fluid is compressed. The automatic-transmission fluid particles in shear transmit torque to the other side. This torque transmission causes the stationary surface to turn, bringing it up to the same relative speed as the moving surface. Since most of the work is done by the fluid particles in shear, by the time the surfaces actually meet, or “lock up,” wear is virtually eliminated.

The Kone experiment went so well that Dorman rebuilt his Landel gear box with a Force Control holding brake two years later. “We’ve never had to change it or do anything other than preventive maintenance to the Landel since rebuilding it,” Dorman said. From arbitrary breakdowns costing weeks in downtime to consistent and predictable uptime lasting more than a decade, the right brakes have put Ohmstede’s maintenance issues on ice.

For more information, visit forcecontrol.com