Controlled Hydraulics

The pump room, located in the basement of the Ketter Hall expansion, houses four MTS 506.92 Hydraulic Power Supply (HPS) units, each rated at 185gpm (700lpm) flow with 3,000psi (207 bar) working pressure. Each HPS consists of two high-pressure, variable volume main pumps and a low pressure “supercharge” pump that draws oil from the reservoir and supplies a constant oil pressure and flow to the inlets of the main pumps.

General Information

These units have oversized reservoirs to accommodate the additional accumulator oil volume required for high performance dynamic testing. Hydraulic system oil is cooled by pumping hydraulic fluid through a system of heat exchangers (one located on each HPS) that are connected to the campus chilled water system. The chilled water is supplied at an average year-round temperature of 50° F. Temperature-sensitive flow control valves are provided by MTS as part of the HPS assembly. These valves regulate the flow of chilled water through the heat exchangers as a function of hydraulic fluid system temperature. The hydraulic fluid is maintained at an optimum working temperature of 100-110° F.


The laboratory hydraulic distribution system is an integrated solution for the combined functions of seismic and structural testing.  The system was designed to minimize system expenditure (by reducing the use of duplication) and to maximize performance and capabilities.

The pump room piping segment is connected to the outputs of the four HPS units and runs directly to the through an opening in the table trench wall. The diameter of the common piping in the HPS room area is 130 mm pressure and 220 mm return line with 2 inch drain lines. The reservoirs of the HPS units are connected together with large diameter piping to provide a common reservoir from which all 8 pumps on the 4 HPS units can draw oil.

The seismic piping system runs along the length of the shake table trench. This piping is sized to allow both the seismic table and structural actuators to run simultaneously for hybrid testing applications with table-mounted specimens coupled with the strong wall at the east end of the trench. Hydraulic outlets with manual valves are located along the trench for positioning of the movable tables, offering maximum flexibility. Outlets are also located along the strong wall for connecting the Hydraulic Service Manifolds for the high flow structural actuators. Flexible hoses are used to connect the table system and the structural actuators to the main hard line distribution outlets.

Four hydraulic outlet stations are located along the table trench for connection of hoses. Two stations are used to connect to the moveable tables at any one time and any free stations can be used to allow connection of structural actuators to the strong floor along the north side of the floor for certain configurations. By design, one trench distribution manifold station will allow one table to be positioned to any one of four locations without breaking hose connections. This helps simplify repositioning of the table system.

The main branch line running from the HPS piping manifold in the table trench area to the east end of the trench is sized to provide in excess of 1200 GPM pressure and 1600 GPM return (average) of oil flow using 150 mm pressure piping and 220 mm return piping with 2 inch drain lines. Wall openings are cast into the concrete structure of the basement and the table trench, through which the hard line is routed.

Over 700 gallons of oil volume accumulation is provided through four distributed accumulation bank systems. These accumulators are located in the basement below the strong floor adjacent to the high flow hydraulic distribution manifolds. These are engineered to operate in a horizontal manner to provide maximum accessibility for maintenance in the basement.

At the end run of the main branch line, a secondary piping distribution runs south below the strong floor along the strong wall to service the structural testing area. This secondary branch line for structural testing also consists of 150 mm pressure piping and 220 mm return line piping with 2 inch drain lines along the length of the strong wall. Line accumulation from the individual Hydraulic Service Manifolds and the basement accumulation banks supplements the flow above the 800 GPM output from the HPS units as needed. Vertical risers run from the basement level through the strong floor to the four distribution manifolds mentioned earlier. The pressure risers are 130 mm and the return risers 140 mm in diameter. Strong floor cut outs (precast in the floor) allow the passage of the piping system from the basement to the top of the strong floor.

At the strong floor surface, adjacent to the strong wall, four high flow manual distribution manifolds are located, with four sets of 2 inch hand and check valves to allow connection to the three moveable Hydraulic Service Manifolds. This arrangement will supply the highest available volume flow to the structural actuators for their demanding applications for real time hybrid and other high-demand testing. These high flow manual distribution manifolds can also be used as general purpose distribution manifolds to connect other actuators for more traditional structural testing applications (when the high flow structural actuators are not in use) adding setup flexibility along the strong wall area.

Beginning at the fourth high flow structural testing distribution manifold location, approximately 60 feet of 75 mm diameter piping runs below the strong floor along the south edge of the floor. Three low flow distribution manifolds are evenly spaced along this piping run and each is provided with two sets of hand and check valves on the testing floor level. The vertical risers consist of 2 inch SST piping (pressure and return) to each distribution manifold.

When considered as a single system, the hard line runs and outlet stations in the table trench, and the hard line runs and manifolds along the strong wall and south strong floor allow hydraulic power to be distributed to three sides of the strong floor area. This distribution scheme allows hydraulic power coverage over the majority of the strong floor area.

Service Manifolds (ports)

Three high flow (800gpm) Hydraulic Service Manifolds with additional accumulation are typically located near the lab reaction wall to provide full flow capacity to the high speed structural actuators. For structural testing applications, these Hydraulic Service Manifolds are used for on/off control with 40 gallons each of pressure and return accumulator banks. These service manifolds each support a single actuator assembly with an 800 GPM servo valve. These Hydraulic Service Manifolds can be positioned throughout the testing Laboratory, with high speed testing typically performed at the lab reaction wall where the distribution piping and accumulator systems will maximize the flow capabilities. They can also be positioned at any free station located at the seismic table trench area if needed.

Each table system has a dedicated integral Hydraulic Service Manifold with 30 gallons each of pressure and return accumulators.

Two (2) 50gpm hydraulic service manifold are available for connecting the static actuators. Typically these manifolds are connected to the south strong floor distribution manifolds; however they can be used throughout the laboratory wherever a connection point exists.

Oil Filtration and Cleanliness

The hydraulic distribution system is designed to meet an oil filtration quality of ISO 13/10. This level of cleanliness is critical for high fidelity servo valve systems. The system is designed to use Mobil DTE 25 hydraulic fluid or the equivalent. Oil samples are taken annually and sent to MTS for evaluation. If particle counts exceed the ISO 13/10 specification, corrective action is immediately taken. This typically involves flushing the hydraulic distribution system at high flow rates for several hours or days, after which oil samples are again drawn for evaluation.