Sundstrand Sauer Danfoss Series 51 and 51-1 Bent Axis Variable Displacement Motors,  for model 51V060 51V080 51V110 51V160 51V250 51D060 51D080 51D110 51D160 51D250 51C060 51C080 51C110 51C160. 
Motor type: Axial piston motor with variable displacement bent axis design.
Direction of rotation: Clockwise and counter-clockwise (bi-directional).
Installation position:  Discretionary, the housing must always be filled with hydraulic fluid.
Other system requirements:    Independet braking system, circuit overpressure protection, suitable reservoir.
Details regarding the choice of hydraulic fluid:     
The correct choice of hydraulic fluid requires knowledge of the operating temperature in relation to the ambient temperature: in a closed circuit the circuit temperature. The hydraulic fluid should be chosen so that the operating viscosity in the operating temperature range is within the optimum range - the shaded area of the selection diagram. We recommended that the higher viscosity class be selected in each case. Example: At an ambient temperature of X °C an operating temperature of 60 °C is set. In the optimum operating viscosity range (shaded area) this corresponds to the viscosity classes VG43 or VG55; to be selected: VG55. Please note: The case drain temperature, which is affected by pressure and speed, is always higher than the circuit temperature. At no point in the system may the temperature be higher than 118 °C. If the above conditions cannot be maintained due to extreme operating parameters, please consult us.