The complete unit comprises six major systems:

一、Power and Transmission System (Diesel-driven side：Diesel Engine：410KW Cummins brand)

1. Diesel engine: Non-road emission compliant diesel engine serving as the unit‘s power source; features a dedicated engine oil circuit (independent of the air compressor gear oil).

2. Highly flexible coupling: Connects the diesel engine output shaft to the input shaft of the dry oil-free air end; dampens vibration.

3. Chassis, mobile towing frame, and tires (specific to mobile models).

4. Sound-attenuating enclosure.
 

This step will involve diesel and engine oil.

① Diesel fuel flow path （There will be a diesel tank.）

 

Main fuel tank (the large tank on the trailer)

↓

Fuel filter element (diesel filter)

↓

High-pressure fuel pump

↓

Fuel injector (nozzle)

*Injected into the **diesel engine cylinder combustion chamber

*Mixes with air; undergoes compression ignition and combustion to generate power

*Drives the piston to move up and down → crankshaft rotates to output torque

*Then, via a flexible coupling, drives the rotation of the dry, oil-free air compressor airend, allowing the compressor to begin compressing air

Diesel fuel circulates only within the diesel engine‘s cylinder combustion chamber and the fuel injection system (high-pressure pump and injectors).

- ✅ After combustion, it turns into exhaust gas and is expelled through the exhaust pipe; diesel does not flow into the lubrication oil circuit, nor does it enter the air compressor!

- ✅ The rotational power output by the diesel engine‘s shaft is what drives the air compressor unit; the diesel fuel itself does not enter the interior of the air compressor airend.

② Internal Oil Circulation Path

The engine features a built-in oil pump (driven by the crankshaft).

Oil sump (oil reservoir at the bottom of the engine) → Oil pump → Oil filter → Various moving friction points within the engine → Return to the oil sump.

Heat Dissipation: A portion of the oil cools the pistons; the heat absorbed by the oil is primarily dissipated via the engine‘s water-cooling system, which incorporates an oil cooler.Internal Oil Circulation Path

The engine features a built-in oil pump (driven by the crankshaft).

Oil sump (oil reservoir at the bottom of the engine) → Oil pump → Oil filter → Various moving friction points within the engine → Return to the oil sump.

Heat Dissipation: A portion of the oil cools the pistons; the heat absorbed by the oil is primarily dissipated via the engine‘s water-cooling system, which incorporates an oil cooler.

Engine oil lubrication points (diesel engine assembly only)

1.  Crankshaft and crankshaft bearings (main bearings)

2.  Connecting rods and connecting rod bearings (big-end bearings)

3.  Pistons, piston rings, and cylinder walls (lubrication and piston cooling)

4.  Camshaft and valve train components (rocker arms, tappets)

5.  Internal engine gears and timing drive components

二、Compressor Air-end System [Core Component-Dry Two-Stage Oil-Free Screw Air-end：GHH/DG brand]

Two-stage dry screw system: 1st-stage compression → 1st-stage cooler → 2nd-stage compression → 2nd-stage cooler → 3rd-stage compression → after-cooler

- Male and female rotors (featuring high-temperature resistant surface coatings; no contact between rotors)

- Synchronous gear set (gearbox): This is the component served by the independent lubricating oil circulation system; the main unit‘s oil inlet feeds directly into the gearbox‘s oil circuit.

- High-precision bearing assembly; airend housing equipped with a cooling jacket (in some models, cooling oil circulates through the housing interlayer to assist with heat dissipation).

❗ There is no lubricating oil inside the compression chamber; oil circulates only through the gearbox, bearings, and housing cooling jacket.

三、 Independent gear-bearing lubrication oil circuit for the air compressor (independent oil pump circuit—not diesel engine oil).

The "main unit oil inlet temperature" listed in the technical specifications refers to the oil temperature measurement point in this circuit, located just before the oil enters the gearbox.

Reference

Sr #	Diesel engine oil	Lubricating oil for dry, oil-free compressor air-end gearboxes
Name of Petroleum Product	Diesel Engine Oil	Fully Synthetic Industrial Gear Oil / Synthetic Turbine Oil
Typical viscosity	15W‑40（SAE）	ISO VG68 / VG100
Storage location	Diesel engine bottom oil sump	External independent gear oil tank of the unit
Lubrication target	Crankshaft, piston, connecting rod, valves (diesel engine block)	Air compressor timing gears, bearings, and air-end housing cooling jacket
additive	Contains detergent-dispersant additives (removes engine carbon deposits)	Anti-wear and anti-oxidation properties; contains no strong detergents or dispersants.
Can they be swapped?	❌ Mutual raising is prohibited.	❌ Mutual raising is prohibited.

四、Compressed Air System (Airflow Path)

 

Air Intake: Ambient air → Main unit intake filter → Intake regulating valve

→ First-stage screw compression (high temperature, approx. 160–180°C) → First-stage cooler → Second-stage screw compression → Second-stage cooler → Third-stage compression → Aftercooler + Water-air separator

→ Unit discharge outlet outputs Class-0 oil-free compressed air

 

Dry screw compressors operate with very high discharge temperatures, making intercooling and aftercooling critical. This unit does not have an oil-air separation tank; do not confuse it with oil-injected models.

 

五、Integrated Cooling and Heat Exchange Assembly (Composite Radiator)

 

Integrated assembly: diesel engine water radiator, air compressor gear oil cooler, first-stage cooler, second-stage cooler, and aftercooler; high-power axial cooling fan.

 

VI. Electrical Control and Monitoring System

 

1. PLC Main Control Unit / Control Panel

2. Various sensors:

- [Main unit gearbox oil inlet temperature sensor] (corresponding to the measurement point in the technical specifications)

- Gearbox oil return temperature; 1st and 2nd stage discharge temperatures; discharge pressure; diesel engine water temperature and oil pressure;

3. Alarm and shutdown protection logic; battery; starting circuit.

 

Simplified Text-Based Flowchart

 

[Diesel Engine] → Flexible Coupling → [Dry Two-Stage Oil-Free Main Unit]

 

*Independent Closed-Loop Lubrication Circuit:

Gear Oil Tank → Oil Pump → Oil Cooler → Oil Filter → [Main Unit Gearbox Oil Inlet Test Point] → Gearbox, Bearings & Housing Jacket → Oil Return to Tank

 

Configuration

No	Name	Brand	CountryofOrigin
1	Air end	GHH/DG	Germany/China
2	Diesel engine	Cummins	USA
3	Controller	Smart Gen	China
4	Push-button switch	Siemens	Germany
5	Terminal block	Airstone	China
6	Safety valve	AFS	China
7	Coupling	KTR	Germany
8	Mid Bracket	Airstone	China
9	Cooler	Airstone	China
10	Sensor	Danfoss/Huba Control	Denmark/Switzerland
11	Coolant Reservoir	Airstone	China
12	Trailer Axle	ZEBON	Zhejiang
13	Transfer case	STIEBELI	ShangHai
14	Inlet Valve Assembly	JUNKE/Stable	China
15	Venturi tube	JUNKE/Stable	China
16	Minimum Pressure Valve	EAGURT/Red Star	China
17	Reliefvalve/Pressure limiting valve	AFS	China
18	Temperature Control Valve	CRT	ShangHai
19	Oil Pipe	Airstone	China
20	Air Filter	Donaldson	USA
21	Oil Filter	Donaldson	USA
22	Lubricating Oil	TPI	China
23	Control Line	Parker	USA
24	Chassis Sheet Metal	Airstone	China