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Marine Problems & Solutions

Special Drive Flanges

PROBLEM

Our customer needed to connect an existing gear and water jet. This installation had two different flange connections, neither of which matched standard universal joint flanges.

SOLUTION

We reviewed the application to identify the proper size shaft, then evaluated the flange configurations. We were able to design flanges to match the existing connections.

In our shop, we were able to press and weld these custom flanges onto tube yokes, thus completing an assembly without any extra hardware.

This universal-joint shaft dropped right into our customer's application, bolted in place ready to run. If you have an oddball installation, give us a call—and we'll see if we can help you.

Gantry Crane Arm Mount

PROBLEM

During an equipment update our customer had the challenge of finding the best way to connect the gantry arm to the base. To complicate matters, the installation was on a ship's deck with heavy exposure to salt water.

SOLUTION

We were able to detail a system which employed a shrink-disc to mechanically lock the arm to the base.

This approach allowed them to position the arm at any desired angle. Additionally, there is no clearance or lash for wear or fretting corrosion.

We also designed a watertight cover to offer additional protection.

This approach not only simplified installation, but down the road it allowed them trouble free removal.

If you have an unusual connection to make, let us know.

Ship Smokes Due To Wrong Coupling

PROBLEM

A vessel's operator contacted us because the starboard clutch had overheated. Within twenty-four hours, we were on board to check it out. This ship was being returned to service after being layed up for two years.

SOLUTION

A review of the propulsion system showed that the clutches were quill mounted in line with the engines. Disassembly of the clutch did not reveal any internal problem that could result in a hangup.

Next we reviewed the original design drawings and there we found a discrepancy with what currently existed. The old design included a pedestal bearing on the forward end of the quill shaft. The installation no longer included this bearing.

This change made a significant difference. With the bearing, the shaft would be fully supported requiring a full (double-flex) coupling. Without the bearing, the appropriate coupling would be a flex-rigid (single-flex) coupling.

When the vessel was returned to service the wrong coupling was installed. Consequently, the assembly whipped and the orbiting clutch plates kept making contact resulting in excessive heat.

They replaced the coupling and the propulsion system is now operating smoothly.

Tug Clutch Update

PROBLEM

Over the life of a vessel, you typically find maintenance costs increasing. Our customer found this particularly true of their forward and reverse clutches.

SOLUTION

We were able to come up with an alternate design which has consistently operated with significantly lower maintenance cost.

In addition, we provided complete installation of the new units. Our crew made all of the final adjustments and participated in the sea trial.

The complete package, start to finish, was important to our customer. If you need a turnkey installation or help anywhere along the way—give us a call.

Drive Overload Protection

PROBLEM

From time to time, the propeller would strike a log or piling instantly shearing the pinion shaft in the reduction gear. This resulted in costly rebuilds and downtime on a regular basis.

SOLUTION

The existing drive configuration, a typically tight marine envelope, limited our options. The close connection between the engine and gear prohibited any high speed approach. This only left the tail shaft connection.

We developed an assembly to handle the 1055 HP (787 kilowatt) diesel drive using only five axial inches. Despite the short length, they will still need to modify the tail shaft or move it aft.

This design will completely disconnect upon overload. The initial unit is adjustable from 127,560 in-lb. (14,412 nM) to 701,580 in-lb. (79,268 nM). We can upgrade to 1,169,300 in-lb. (132,113 nM). (With the installation of additional elements, we are evaluating both taper roller and sleeve bearing designs).

Torsional Vibration Damages Tug Clutch

PROBLEM

This customer had just replaced the friction plates in his forward and reverse clutches. The next morning they had picked up a barge and had headed out the inlet. Shortly after reaching full ahead, smoke began to fill the engine room. Unable to stop in the inlet, they had to proceed out several miles.

When the smoke cleared, they found the reverse clutch was red hot. After limping back into port, disassembly revealed severely worn friction material.

They checked their air control valves and circuits to see if they could explain why the reverse clutch smoked while going forward.

They couldn't figure out what happened, so they asked us to visit.

SOLUTION

Within 24 hours, we were on site. Sure enough, a lot of friction material was missing, however the wear surfaces didn't exhibit normal rubbing contact. The air tube had literally burned at one point, yet the other metal parts did not have the expected "blueing".

After collecting all the data, we got on the phone with Ron Compton, who has considerable experience with similar propulsion systems. He gave us a couple more parts to the puzzle.

We then checked the pilot bearing clearance, and as suspected we found that it had opened up 0.008". Turns out that this particular engine and gear box has a critical torsional frequency near the full ahead speed. If the shaft is not properly restrained (proper bearing fit), it will whip. This action rapidly and violently throws the clutch plates back and forth, resulting in heat and impact failures of the friction material.

Due to the critical need for this vessel, we needed to get up and going ASAP. The bearing bore was bushed and machined to the proper tolerance. The center plates were cleaned and checked for flatness. The air tube and friction plates were replaced. By the next morning, she was back at sea.

If you have a problem which is tough to explain, give us a call.

Shipyard Crane Brake Upgrade

PROBLEM

Our customer is a large shipyard operating over 400 cranes and the operation is over 100 years old. A number of these cranes and brakes are now obsolete. This makes maintenance extra tough.

They had one brake which required continuous attention and still couldn't meet the current requirements. They turned to us for a solution.

SOLUTION

A careful review of the application revealed that the biggest challenge was a lack of space. A tight envelope eliminated most of the current brake designs.

After researching a significant number of designs, we came up with a caliper disc hoist brake for the application. This approach with a disc brake provided increased torque and thermal capacity. Its compact design allowed us to meet their envelope restrictions.

By upgrading the hoist brake, the yard will be able to use this crane well into their next 100 years.

Ferry Boat Propulsion Clutch Life

PROBLEM

Our customer operates three ferries around the clock, year round. They are able to schedule dry-docking one at a time, and only one vessel per year. They are faced with making repair/replacement decisions to guarantee no downtime, but faced with a limited budget.

SOLUTION

We were retained to oversee the removal, rebuild and reinstallation of the propulsion clutches.

In dry-dock, we were able to review their detailed maintenance history. Upon dis-assembly, we inspected the existing friction shoes and drum working surfaces. Taking dimensional data, we compared the original factory specs with existing values. We compared the original factory specs with existing values. Based on this data, it was determined that the clutches had two-thirds of their useful life remaining.

Our customer was able to re-assemble and return to service with minimal cost, confident that the next three years would be trouble-free. We can help you keep going and stay within budget.

Torsional Vibration Damages Tug Clutch

PROBLEM

This customer had just replaced the friction plates in his forward and reverse clutches. The next morning they had picked up a barge and had headed out the inlet. Shortly after reaching full ahead, smoke began to fill the engine room. Unable to stop in the inlet, they had to proceed out several miles before stopping.

When the smoke cleared, they found the reverse clutch was red hot. After limping back into port, disassembly revealed severely worn friction material.

They checked their air control valves and circuits to see if they could explain why the reverse clutch smoked while going forward.

They couldn't figure out what happened, so they asked us to visit.

SOLUTION

Within 24 hours, we were on site. Sure enough, much friction material was missing, however the wear surfaces didn't exhibit normal rubbing contact. The air tube had literally burned at one point, yet the other metal parts did not have the expected "blueing".

After collecting all the data, we got on the phone with Ron Compton, who has considerable experience with similar propulsion systems. He gave us a couple more parts to the puzzle.

We then checked the pilot bearing clearance, and, as suspected, we found that it had opened up 0.008" (0.203mm). It turns out that this particular engine and gear box has a critical torsional frequency near the full ahead speed. If the shaft is not properly restrained (proper bearing fit), it will whip. This action rapidly and violently throws the clutch plates back and forth, resulting in heat and impact failures of the friction material.

Due to the critical need for this vessel, we needed an immediate solution. The bearing bore was bushed and machined to the proper tolerance. The center plates were cleaned and checked for flatness. The air tube and friction plates were replaced. By the next morning, she was back at sea.

If you have a clutch problem which is tough to explain, give us a call.