Copyright Goodheart-Willcox Co., Inc. 184 Fluid Power The pump is placed close to the fl uid supply, minimiz- ing inlet line pressure drop. Locating the power unit on the reservoir requires the addition of a metal sup- port plate and other fi ttings to facilitate attachment. In larger-capacity units, the weight of the pump and prime mover become important factors in determining the strength of the structural members of the reservoir and the mounting plate. When placing a reservoir in use for the fi rst time, a great deal of care should be taken to be certain the inside of the tank is clean. Any machining chips and welding slag obviously should be removed as well as any cutting oils. The inside of the tank should be fi n- ished with a material that will withstand the chemical characteristics of the fl uid used in the system. It must also be able to withstand the chemical activity pro- moted by contaminants that enter the system during equipment operation or cleaning. 8.1.3 Reservoir Confi gurations A rectangular tank with the pump located above the fl uid level is probably the most commonly used form. This confi guration is found in both station- ary and mobile hydraulic-powered equipment. The requirements regarding reservoir construction can easily be met using this form. However, other system fl uid level in the tank to prevent the formation of a vortex. A vortex is a whirlpool that can form around the inlet line if the pickup is too close to the fl uid surface. In extreme cases, a vortex can actually allow air to be drawn into the pump. Also, the inlet should be placed at least 1″ from the bottom to minimize recirculation of sediment from the bottom of the tank. The return line returns fl uid from the operating circuit back to the reservoir. The return line should be large enough in diameter so fl uid velocity is not exces- sive during the maximum-expected return fl ow. It must always be positioned on the opposite side of the baffl e from the inlet line. A common practice is to cut the end of the return line at a 45° angle. The return line should end approximately two pipe diameter off the bottom of the reservoir. The sloped end should be posi- tioned to cause the fl uid to circulate along the sides of the tank. The drain return line returns fl uid drained from externally drained components to the reservoir. It must provide drainage with a minimum of back pressure. This is necessary as drainage from components needs to escape as easily as possible to allow effective opera- tion and lubrication. The top surface of the reservoir is often used as the mounting base for the system power unit, Figure 8-4. Mounting pad Pump Reservoir Prime mover Used with permission of CNH America LLC Figure 8-4. The reservoir is often used as a mount for the system prime mover, pump, and other system components. The tank must be made from adequately strong material to support these units.