Knowledge base
A mechanical driven radiator is the cooling system that comes with the engine: a radiator core mounted on the generator set frame in front of the engine, and a fan driven from the crankshaft by a belt or a shaft pulling or pushing air through the core. It needs no electrical supply, no controls and no separate plant, which is why it is the standard solution for many generator sets. This guide explains how it works, what it gains, and the limits that decide when a remote radiator with electric fans is the better choice.
How It Works
The coolant leaves the engine, passes through the finned core of the radiator and returns to the engine pump. The fan, mounted on the front of the engine on a belt-driven hub or on a shaft, turns whenever the engine turns; it draws the air through the core and blows it out through a shroud and, usually, a duct to the outside of the room. The engine room is ventilated by the same air flow, which enters through a louvre at the back of the room, passes over the alternator and the engine and reaches the fan.
For an engine with two circuits the radiator core carries both an HT and an LT section, in the same way as a remote LT/HT radiator. The core is built for the engine maker's flows and temperatures and for the air flow the fan delivers at the engine speed.
What It Gains
Independence is the first gain: the fan runs because the engine runs, so cooling needs no mains, no inverter, no control cabinet, and keeps working in a black start or when the site has lost its electrical supply. The second is compactness: the radiator, fan and shroud sit on the set frame and are delivered, transported and installed as part of it, with short pipe runs and no external plant. The third is simplicity: fewer components, no separate fan motors to maintain, and a coolant circuit that is complete when the set arrives.
Where It Stops Being The Right Choice
The fan speed follows the engine speed, so the air flow cannot be adjusted to the load or the ambient: the fan moves the same air at part load on a cool night as at full load on the hottest day, which costs fan power and noise. That power comes from the engine and is not available to the load. The noise is made at the engine, inside or next to the room, which is harder to attenuate than a remote radiator placed where the sound limit allows.
The air path is also limited. The fan can overcome only a modest external restriction - the louvres, the duct, the ducted outlet - before its air flow drops, and a long duct or fine louvres can starve the core. Large engines and long pipe runs outgrow the engine-mounted solution: the radiator becomes too big for the set frame and the air flow too large to pull through the room, and the cooling moves outside as a remote radiator with electric fans, speed controlled to the load.
Where It Is Used
Standby and prime generator sets of small and medium power, packaged and containerized sets, portable and mobile sets, and sites where electric fan power is not wanted or not available. The engine maker's own air flow and restriction limits set the boundary; TECS designs the core, the shroud and the frame to the engine data sheet and to the site ambient, with the same coolant, material and corrosion options as the remote radiators.
TECS Engineering builds mechanical driven radiators for generator sets alongside its horizontal and vertical remote radiators and V-type units. Send the engine data sheet, the site ambient, the room and duct layout, and the proposal states the core, the air flow and the restriction it can carry.
In Short
- Radiator core on the set frame, fan driven by the engine through a belt or a shaft
- No electric supply or controls; works in a black start
- Fan speed follows engine speed: the air flow cannot follow the load or the ambient
- Fan power comes from the engine, not from the load
- Noise is made at the engine; the external restriction the fan can carry is limited
- Large duties and long ducts move to remote radiators with electric fans
What To Send With An Enquiry
- Engine data sheet: heat duty, flows, temperatures, allowed pressure drop
- Engine speed and the fan drive: belt or shaft, fan diameter
- Site ambient, altitude and the hottest ambient at full load
- Room layout: inlet louvre, outlet duct and their restriction
- Corrosion class and the coolant mixture
- Whether the set is packaged, containerized or in a building
Questions We Are Often Asked
What is a mechanical driven radiator?
A radiator mounted on the generator set in front of the engine, with a fan driven directly from the engine by a belt or shaft, so it needs no separate power supply.
Why is it also called an engine-mounted radiator?
Because it stands on the generator set frame as part of the set, with the fan driven by the engine, as opposed to a remote radiator that stands elsewhere with its own electric fans.
Does the fan take power from the generator?
It takes it from the engine crankshaft, so that power is not available to the load.
Can the fan speed be controlled?
Not independently: the fan speed follows the engine speed. A remote radiator with EC or inverter-driven fans adjusts the air flow to the load and ambient.
When should a remote radiator be chosen instead?
When the duty is large, the sound limit is strict, the room cannot supply the air flow, or the radiator has to stand away from the engine.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
