The CMM-GL unit is designed to drain used oil from and pump new oil into wind turbine gearboxes[mfn]A gearbox is typically used in a wind turbine to increase rotational speed from a low-speed rotor to a higher speed electrical generator.[/mfn]. The unit can also flush[mfn]The term “oil flushing” is used extensively in the process heating industry to refer to the cleaning of pipes and process equipment.[/mfn] the gearbox with special oil. The machine can service main and azimuth gearboxes, as well as blade angle of attack gearboxes.

The unit operates with mineral[mfn]Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum.[/mfn] and synthetic[mfn]Synthetic oil is a lubricant consisting of chemical compounds that are artificially made. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials[/mfn] gearbox oils with the following specifications:

• kinematic viscosity[mfn]The viscosity of a fluid is a measure of its resistance to deformation at a given rate.[/mfn] at 40°С  – 8…50 mm²/sec;
• density[mfn]The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume.[/mfn] at 20°С – 800…950 kg/m³;
• ISO [mfn]The International Organization for Standardization (ISO) is an international standard-setting body composed of representatives from various national standards organizations. [/mfn] 4406 purity class – -/19/16 or better.

CMM-GL gearbox oil changer design

The СММ-GL is a trailer with one axle, which supports the control section and the process section. The process section also includes hose reels. Control section doors are equipped with secure locks.

The unit requires an external power source. The CMM-GL is fully automated with a special controller, which manages operation of pumps, valves, capacitance sensors, temperature sensors, flow switches, filters[mfn]An oil filter is a filter designed to remove contaminants from engine oil, transmission oil, lubricating oil, or hydraulic oil.[/mfn], manometers[mfn]A Manometer isa device to measure pressures.[/mfn] and flow meters.

Modes of operation

Used oil drain mode

In this mode, the vacuum pump[mfn]A vacuum pump is a device that removes gas molecules from a sealed volume in order to leave behind a partial vacuum.[/mfn] extracts oil from a gearbox into the vacuum chamber until the chamber is full. Then a gearpump transports the oil to a prepared container.

Gearbox flushing mode

In this mode, oil is supplied by the gearpump to the required elevation (up to 60 meters) and is injected into the gearbox under pressure, washing away the remaining old oil and particulate matter.

New oil supply mode

In this mode, the gearpump supplies oil to the required elevation (up to 60 meters).

Filtration mode

While pumping new or flushing oil into the gearbox, the oil passes through a 15 μm[mfn]The micrometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known by the previous name micron, is an SI derived unit of length equalling 1×10−6 metre (SI standard prefix “micro-” =10^-6); that is, one millionth of a metre (or one thousandth of a millimetre, 0.001 mm, or about 0.000039 inch).[/mfn] filter for enhanced purity.