Technical Project Summary | Benton Harbor Michigan

MDOT Drawbridge Hydraulic Cylinder Rebuild

MDOT Drawbridge Hydraulic Cylinder Rebuild in Benton Harbor, Michigan

Project Specifications

Project result  US Hydraulics rebuilt eight drawbridge cylinders, replaced three overpressurized barrels, manufactured upgraded components, completed documented 5,000 psi testing, and supported a hydraulic manifold redesign. After installation, the customer reported that the system operated better than it had in years.


Customer Success Story:

Engineering and Inspection Scope

Because the work supported a state funded infrastructure project, US Hydraulics developed technical documentation for MDOT review and approval before production.

  • Reverse engineering of the original cylinder components
  • Detailed repair procedures and component drawings
  • Material selection and replacement part design
  • Machining welding inspection and pressure testing procedures
  • Documented measurements inspections and final repair history


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    Original drawbridge cylinders received for disassembly and inspection.


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    Large cylinder positioned for controlled disassembly and dimensional inspection.


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Barrel Replacement and Certified Welding

Inspection identified three cylinder barrels damaged by overpressurization. The barrels could not be safely returned to service and were replaced.

New cylinder barrel material was secured.

Original end flanges were recovered and prepared for reuse.

A properly certified welder joined the original flanges to the new barrels.

Required weld areas underwent magnetic particle inspection and passed.

Custom Component Manufacturing

US Hydraulics reverse engineered the original glands and machined eight replacements from forged material selected for greater strength than the original components.

  • Eight new forged glands machined to the required sealing and mounting dimensions
  • All cylinder rods industrial hard chrome restored and polished by a qualified outside vendor
  • New seals wear components and end bearings installed during assembly


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    Original gland and newly manufactured forged replacement.


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    Precision machining of a replacement cylinder gland.


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    Completed forged glands prepared for final inspection and assembly.


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    Machining a large cylinder component to documented dimensions.


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    Cylinder assembly using restored and newly manufactured components.


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    Final machining work on a large cylinder component.

    of a replacement cylinder gland.


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    Rebuilt cylinder with the restored rod extended during final inspection.


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    Completed cylinders following testing bearing installation and coating.


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Assembly and Pressure Testing


Each cylinder was assembled with restored or newly manufactured components and completed under the approved repair process.

  • New seals wear components and end bearings installed
  • Rechromed and polished rods installed
  • Each cylinder tested at 5,000 psi for 30 minutes in the extend direction
  • Each cylinder tested at 5,000 psi for 30 minutes in the retract direction
  • Completed cylinders painted to MDOT specifications


Hydraulic Manifold Redesign


The customer later requested replacement hydraulic manifolds. US Hydraulics worked with its manufacturing supply chain to evaluate the existing design and produce new custom machined manifold blocks for the bridge system.



Final Deliverables


  • Eight fully rebuilt hydraulic cylinders
  • Three replacement cylinder barrels using recovered original end flanges
  • Eight upgraded forged cylinder glands
  • Eight restored and polished chrome rods
  • Certified barrel welding with passed magnetic particle inspection
  • New seals wear components and end bearings
  • Documented 5,000 psi pressure testing
  • MDOT specified coatings
  • Newly designed and machined hydraulic manifold blocks
  • Complete repair inspection and history records


Project Result


All eight cylinders and the replacement manifold blocks were delivered with the required documentation. Following installation, the customer reported that the drawbridge hydraulic system was operating better than it had in years.

US Hydraulics Capabilities


US Hydraulics provides large hydraulic cylinder rebuilding, reverse engineering, custom machining, certified welding, component manufacturing, manifold design, and documented pressure testing for industrial equipment, mobile machinery, construction equipment, municipal infrastructure, and obsolete hydraulic systems.