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A2FO
REXROTH
Hydraulic oil
HFA is not applicable to the A2FO quantitative system. When using HFB, HFC and HFD or environmentally friendly hydraulic oil, consider the restrictions on technical data and sealing in RC 90221 and RC 90223. Please specify the type of hydraulic oil used when placing an order.
Working viscosity range
To achieve the best efficiency and service life, we recommend selecting the working viscosity (at the working temperature) within the following range:
vep:= Optimal viscosity 16... 36 mm 2/s
The above is for the tank temperature (in the open circuit).
Viscosity limit range
The limit viscosity values are as follows:
Specification 5...200: Vmin=5 mm? /s
For short periods (less than 3 minutes), operate at the maximum allowable temperature. tax= +115°C.
Vma=1600mm2/s.
Short-term (t < 3 minutes) cold start (p < 30 bar, ns 1000 rpm) tmm=-40°C).
Specification: 250..1000: Vmin= 10 mm? /s,
For short periods (less than 3 minutes), operate at the maximum allowable temperature. tmax= +90°C
Vma= 1000 mm2/s.
Short-time cold start (t < 3 minutes) (p ≤ 30 bar, n ≤ 1000 rpm, t = -25°C)
Please note: The maximum hydraulic oil temperature must not exceed (even locally) (for example, in the bearing area). The temperature in the bearing area is related to pressure and rotational speed and is 12K higher than the average oil temperature of the housing.
Special measures are required when the temperature is between -40°C and -25°C. Please contact our company.
Hydraulic Oil Selection Instructions
To make the correct selection of hydraulic oil, it is necessary to understand the working temperature related to the ambient temperature. In open circuits, the working temperature refers to the temperature of the oil tank.
Hydraulic oil should be selected in such a way that within the working temperature range, the working viscosity is within the optimal range (V.) (see the shaded area in the selection chart). We recommend that in each case, the highest viscosity range should be chosen as much as possible. Example: At an ambient temperature of X°C, the working temperature in the circuit is 60°C. Within the optimal working viscosity range, the corresponding viscosity levels VG46 or VG 68 should be selected, and VG 68 should be chosen.
Please note: Due to the influence of pressure and speed, the temperature of the leaking oil is always higher than the temperature of the oil tank. However, the temperature at any point in the system cannot exceed 115°C (specification 5 to 200) or 90°C (specification 250 to 1000).
If the above conditions cannot be achieved due to extreme working parameters or higher ambient temperatures, we recommend flushing the bearings through the oil port U (specification 250 to 1000). Filtering
The cleaner the hydraulic oil is filtered, the higher the cleanliness of the oil will be, and the longer the service life of the axial piston elements will be.
To ensure the normal operation of the components, the minimum cleanliness grade should be at least 20/18/15 as per ISO 4406.
At very high hydraulic oil temperatures (90°C to a maximum of 115°C, not allowed for specifications 250 to 1000), the cleanliness grade of the hydraulic oil should be at least 19/17/114 as per ISO 4406. If the above cleanliness grades cannot be achieved, please contact our company.
Allowable pressure load
The service life of the shaft sealing ring is affected by the pump's rotational speed and the pressure of the shell's oil discharge. The allowable load under intermittent shell oil discharge pressure is related to the rotational speed. The maximum allowable pressure value for short periods (t < 5 min) is 10 bar absolute pressure.
The average long-term shell oil discharge pressure must not exceed 3 bar absolute pressure.
The pressure inside the shell must be equal to or greater than the external pressure on the shaft sealing ring.
Temperature range
Fluorine rubber shaft seals are applicable within the following temperature ranges: -25°C to +115°C (specification 5...200) and -25°C to +90°C (specification 250...1000).
Note: When the temperature is below -25°C, nitrile rubber shaft seals must be used (allowable temperature -40°C to +90°C). For the special model of specification 250...1000, please contact our company.
Installation and Commissioning Instructions
Overview
During startup and operation, the pump body must be fully filled with hydraulic oil (completely filling the housing cavity). The pump must be started at low speed and run without load until all the air in the system is completely expelled. If the operation is stopped for a long time, the oil in the housing will leak through the working oil pipe. Therefore, when restarting, it is necessary to ensure that the housing is fully filled with hydraulic oil. The leaked oil in the housing cavity must be drained through the highest oil drain port of the housing to the oil tank. The minimum suction pressure of the oil inlet port S must not be lower than 0.8 bar (absolute).
Installation location
Choose freely.
The pump is below the lowest oil level in the tank (standard)
Before starting, add oil to the axial piston pump installation position 2 through the highest shell drain port (shaft upward): For position 2, ensure that the pump body is completely filled with oil before starting. Exhaust must be carried out at the oil ports R (specification 10 to 200) and U (specification 250 to 1000). Air bubbles in the bearing area can damage the axial piston pump.
Recommendation: Fill the suction pipeline
Run the pump at low speed until the system is completely evacuated of air
Minimum immersion depth of the drain pipeline in the tank: 200mm (relative to the lowest oil level in the tank)
The pump is higher than the lowest oil level in the tank
Follow the same installation steps as for the bottom-mounted installation, with the additional steps for positions 1 and 2: If the pump is shut down for a long time, hydraulic oil may leak out of the housing through the working pipeline (air enters the housing through the shaft seal). When the pump restarts, the bearings will not be fully lubricated because of this. Therefore, before restarting, please fill the axial piston pump with oil through the highest oil drain port of the housing. Installation position 2: The exhaust must be carried out at the oil outlet R (specification 10 to 200) and the oil outlet U (specification 250 to 1000).
Additional steps for installation position 2 (bearing upward): In this installation position, even if there is still oil in the housing cavity, the bearings still cannot be fully lubricated. To prevent the oil in the housing from leaking out through the oil drain ports, a one-way valve (opening pressure 0.5 bar) can be installed on the drain pipe.
