T468-6.3.2 Hydraulic Cylinders
A. Provide hydraulic cylinders with double trunnion cardanic ring gimbal type mounting arrangement as shown in the plans. Cylinder rods shall be capable of moving up to 20 degrees off centerline in any direction. Submit complete details and calculations for cylinder and mounting arrangement as described below.
B. Hydraulic cylinders shall be of heavy duty mill type design conforming to AASHTO Movable Specifications and ASME B31.1 of the mid trunnion mounting type shown in the Plans. Provide cylinders’ design rated for a minimum of 3000 PSI. Cylinders shall have 2.5” bore, 20” stroke, and 1.38” rod diameter as indicated in the plans with SAE ports. Provide cylinders with the cylinder head and end cap bolted to the body flange. Screwed heads and caps are not allowed.
C. Design and construct cylinder actuator piston rods to provide a minimum Factor of Safety of 3.0 against buckling per AASHTO Buckling requirements. Factors of Safety shall be based on a maximum working pressure equal to the maximum pressure protection setting at the cylinder relief valves. Provide piston rods of high strength carbon steel with corrosion resistant nitriding surface finish or nickel chrome overlay. Standard chrome plated rods are not acceptable. Alternate rod material of 17-4 stainless steel is acceptable if it can meet buckling requirements. Submit calculations to support rod selection per above requirements.
D. Rod Seals and Bearings: Provide a sealing system that includes dynamic seals capable of near zero leak at both low and dynamic high pressure. Suitable wear-rings or gland bushings shall be provided to insure proper guidance of the rod, to insure alignment, and provide ample bearing area to prevent side-loading.
E. Provide hydraulic cylinder with a rod eye that is a non-lubricated type spherical bearing with stainless steel housing.
F. Provide a cardanic ring mounting support bracket that will accept the trunnion mounted hydraulic cylinder. Cardanic ring to be fabricated from A572 Grade 50 steel with composite bearings that do not require lubrication. Cylinder rod must be capable of actuating up to 20 degrees off centerline in any direction. Submit design calculations showing cardanic ring and bearings can operate with a minimum safety factor of 2 based on cylinder design ratings above.
G. Complete actuator to be primed and finish painted with two-part marine epoxy coating.
H. Shop testing of the actuator to 3000psi in both directions is required.