General Information about
Central Lubrication Systems
Single-line centralised lubrication systems are typically used for consumable lubrication.
The lubricant is distributed to the individual friction points in volumetric doses as they operate intermittently in the medium pressure range (20 - 100 bar)
CONSTRUCTION
The central lubrication pump draws the lubricant from a lubricant reservoir via the suction pipe and delivers it under pressure via the filter, main pipe and distributor to the meter valves. From there, the lubricant is metered volumetrically via the lubrication point pipes to the friction points, regardless of viscosity and system size.
Control and monitoring devices are added for automatically operating systems.
FunCtion
The central lubrication pump briefly pressurises the lubricant in the main pipe to ensure that the pressure impulse (lubrication impulse) also reaches the most remote metering valve.
The main pipe is then depressurised to a low residual pressure via the central lubrication pump. Relieving the main line is necessary for the metering valves to function.
The next pressure impulse may only occur when the metering chambers of the metering valves are refilled. This depends on the consistency of the lubricant and the dose quantity.
Metering Valves
Metering valves are used for volumetric delivery of the lubricant to the lubrication points.
In the event of a pressure pulse, the piston, which is guided with play in the housing bore, leaves its rest position. It displaces the lubricant in front of the piston via the ball check valve into the lubrication point pipe. When the end position is reached, the piston point seals the metering chamber in the direction of the non-return valve.
After the pressure is relieved, the piston spring pushes the piston back to its rest position, whereby the metering chamber is refilled with lubricant via the annular gap between the piston and the housing bore. The non-return valve prevents the lubricant from flowing back out of the lubrication point line. Every single metering valve is subjected to careful testing of the function and metering quantity.
Piston Pump / Gear Pump
The piston pump of the TEKAWE- Centralised Lubrication System delivers the lubricant at the required pressure into the main pipe with each stroke. This ensures that the main pipe is relieved after the pressure keeping period, which is important for the function.
The reciprocating pump consists of the pump cylinder with piston and return spring as well as the screwed-on valve housing, which contains all the necessary valves and the connections for the suction pipe and main pipe.
With the gear pump, the drive motor is controlled via a switch/contactor and drives the gear pump via the coupling. This draws in the medium via the suction pipe and conveys it into the main pipe via the valve. After switching off the drive motor, the main pipe is depressurised to a residual pressure.
Operating Range
Lubricants
TEKAWE-Single Line Systems are designed to transport and dose mineral oils with a viscosity range of 10 to 750 mm2/sec at working temperature in a volumetric manner. The minimum viscosity for gear pumps is 70 mm2/sec. In certain instances, the range may be extended to 1500 mm²/sec and to greases approved by us.
Decisive are
- the POURPOINT (°C) according DIN 51597
- or the flow pressure (mbar) according DIN 51805
- and the expansion behaviour (bar) according DIN 51816, part 2.
Lubricants approved by us are suitable for use in lubrication systems with a lower temperature limit of -20 °C and an upper temperature limit of +80 °C. Mineral oils without aggressive additives are authorized as actuating fluids for the hydraulic piston pump. Please contact us before using synthetic oils.
OPERATING PRESSURES
Please be advised that the maximum permissible system pressure of a TEKAWE feed system is 100 bar. The actuating pressures for pneumatically and hydraulically actuated piston pumps are specified in accordance with the relevant standards. During the factory assembly process, the built-in pressure relief valve of these pumps is blocked to ensure optimal pressure build-up throughout the entire system.
It is important to note that for hydraulically actuated pumps, the permissible residual actuation pressure must be observed.
Gear pumps reach a maximum pressure of 30 to 35 bar.
For manually operated pumps, the built-in pressure relief valve is set to 50 bar to minimize the actuating force. It is essential to operate the hand lever quickly. The pipes must be adjusted to the system pressure.
When using TECALAN pipe, it is essential to consider its pressure-temperature behaviour and volume absorption under pressure.
PIPe LENGTH
The possible line lengths are determined by the volume absorption, the operating temperature and the properties of the lubricant.
All pipes should be kept as short as possible.
The length of the main pipe should be limited so that a minimum pressure of 20 bar is reached at the end of each line during the lubrication pulse. During the pause time, the pressure must fall below 4 bar. This results in the following reference values:
Low-viscosity oils and metal pipes: Length 50 m
High-viscosity and consistent lubricants (adhesive oil and greases): Length 20 m
Lubrication point pipe: Length 3 m
Suction pipe: Length 3 m
Suction height: 2 m