Shipbuilding

Naval shipbuilder providing vessels worldwide to over 30-navies identify Doerfer's Wheelift® IP-SPMT transporters for confined space indoor hull assembly of advanced warships within their shipyard.

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Congestion and overhead crane limitations lead a worldwide ship builder to look at alternate work methods for their modular build processes. Early evaluations identified inherent limitations in many of the traditional shipyard work processes. Conventional SPMTs lacked maneuverability to operate as desired in the congested assembly areas. Safe work practices were becoming difficult and expensive to achieve. Process control, future process flexibility and delivery efficiencies were fast becoming key drivers. Fast, precision alignment became even more of a new critical requirement.

Much smaller and more maneuverable, self-loading transporter(s) quickly became the solution of choice. This strategy drove a plan for applying four 300,000 lb. capacity Wheelift transporters for use individually, or in tandem operating multiples depending on the load carrying requirements.

Each of the transporters would be supplied with oversize wheels and an extended travel to handle the floor offsets, in-floor rails and slopes in existence around the construction and assembly halls. With their precision zone controlled fluid equalizing suspension, the axles in each zone have interconnecting fluid lines that allow the pressure to equalize between axles to assure that every wheel carries only its specific share of the load, regardless of variations, slopes, and irregularities in the floor surfaces. Floor loading is dispersed with ground pressure loads spread over a wide footprint.

The precision equalizing suspension with precision zone control would allow ship sections to move into alignment position, then have full control of lift, lower, yaw, pitch and roll as massive hull section move the last thousand of an inch to precisely mate with the fixed section. The Wheelift transporters have the capability of holding and adjusting as necessary as the master butt welds are made and the support blocking is made solid.

Challenge:

To move a wide variety of sizes and weights of modular hull sub-assembly loads throughout the shipyard assembly building's highly confined and congested manufacturing spaces, along with providing precision all-plane positioning and alignment for the joining of hull modules in final assembly operations.

Solution:

Apply (4) self-loading 150-ton capacity Wheelift transporters, each capable of operating independently, paired, or grouped together, working and communicating as a single 600-ton capacity transporter controlled via a single wireless controller when operating in tandem.

Benefit:

• Increased production and product capacity
• Increased plant utilization through elimination of dead travel areas
• Process and equipment flexibility
• Precision assembly processes achievable

Process-driven features include a flat load deck at 26" for product access from any direction, 6% slope capability, 8" vertical travel for precision aligning, self-loading and surface compliance, weatherproofing for travel outdoor, all-wheel drive, 480V, 3PH all-electric from the onboard LP engine/generator packages, umbilical cord power backup cable, wireless control, and fire suppression plan.

For the heaviest loads, 2, 3, or 4 transporters are positioned under the product frames, and a communication link is established. The resulting positioning values are transmitted into one of the transporter's SynchroSteer computers. One unit becomes the "master" and the adjacent units become "slaves" allowing the 8-axle transporters to function as a single 32-axle, 64-wheel, Wheelift transporter with fully synchronous omni-directional steering. Movement of the tandem grouped transporters is achieved via the same single hand-held wireless joy-stick controller.

While traditional self-propelled modular transporters (SPMT) are well know to shipbuilding, Wheelift's IN-PLANT versions (IP-SPMT) provide even higher load carrying capacity on smaller diameter, solid urethane tires. The resulting much smaller and much lower deck heights make the Wheelift IP-SPMTs much for capable for massive assembly operations in confined spaces. The smaller, more agile, IP-SPMTs provides a degree of flexibility not obtainable with the conventional over-the-road capable SPMTs. Wheelift transporters and AGVs enable manufacturing flexibility with configurable work processes facilitating new design freedoms that benefit worldwide niche markets.

Wheelift Transporters and AGVs are manufactured in central Iowa custom engineered to application specific requirements. Chassis and fixtures are available with load capacities to 500+ tons and deck heights as low as 18". Power options include diesel, LP gas, battery, or umbilical cord. Computerized all electric omni-directional drives are standard with individual axle ratings of 15, 20, or 25-ton.

Wheelift® is a Doerfer Companies technology: Doerfer engineers and builds application specific manufacturing machinery and systems. Operating from four North American locations with over 700,000 sq. ft. and 800+ employees, Doerfer offers expanded technical and manufacturing resources, is NQA-1 certified, and follows ISO 9001 standards.

TRADEMARKS

The following terms that are used through this website: Wheelift^®, Uniload^®, SynchroSteer^®, StackAxle^®, TrackAxle™ and OmniAxle^™ are all trademarks that are exclusively licensed to Doerfer Companies.