Amendment_0003.pdf

Amendment 0003

1. The documents appear to allow either hardened steel or stainless steel piston rods.

Which is preferred?

Response: Hardened steel. Please refer to section 2.3.4 quoted here:

2.3.4 Piston Rods

The material shall be selected from ERDC/CERL TR-02-7, Table 3 or a material submitted and approved equivalent to that shown in the table. The rod must be case hardened to 50-54 Rockwell C, polished to a 0.25 micrometer 10 microinch RMS surface finish or better, and nickel and hard-chrome plated to 75 micrometer 0.003 inch minimum thickness. The final rod surface after chrome plating shall be compatible with the seals being used so as to result in zero leakage past the seals.

2. The drawings provided include trunnion and gimbal assemblies. Are we to provide new ones?

Response: We are interested only in the cylinders/eyes. The drawings regrettably may have raised concerns. Please refer to section 1.2, a part of which is quoted here:

1.2 REFERENCES

The publication listed below forms a part of this specification to the extent referenced. The publication is referred to within the text by the basic designation only. The drawings provided are included for reference only.

The drawings refer to the hydraulic cylinders produced circa 1952 and to the miter gate hydraulic cylinders produced circa 1997.

Additionally section 2.3, a portion of which is quoted here:

The hydraulic cylinders shall be of the type designed and manufactured to meet the criteria stated in paragraph Principal Design Parameters. The bore, stroke and mounting style of the cylinders shall be as those in operation at the Troy Lock.

3. Technology has progressed and some items like seals have been improved. Are we to match exactly the existing cylinders?

Response: No, the new cylinders are to meet the fit, form and function of the existing cylinders.

Please refer to section 2.1, quoted here:

2.1 Principal Design Parameters

The contract drawings indicate the general design, dimensions and features of the existing hydraulic cylinders. The new hydraulic cylinders shall be fabricated and assembled so as to universally meet the fit, form and function of the existing cylinders. The new hydraulic cylinders shall be able to withstand the maximum operating pressure in the system (2000 psi) with a factor of safety of five (5) based on the ultimate strength of the material or two (2) based on the yield strength of the material. A factor of safety of three (3) shall be applied to the compression load when designing the hydraulic cylinder to resist buckling. Prospective bidders are encouraged to visit the Troy Lock and Dam site, located at 1 Bond Street, Troy, NY 12180 to inspect the existing hydraulic cylinders and record any measurements needed, as the drawings provided are for reference only and the hydraulic cylinders to be provided are similar to those in operation at the lock. The successful bidder is required upon award to conduct a site visit and verify the conditions and hydraulic cylinder dimensions and materials as currently constructed.