NMX‑ACT‑30 / Rev 00 / ground support & environmental control / heat load · delivery · mobility 2026 · Product Page

NMX-ACT-30 · ENGINEERED TO ORDER — MOBILE AIR-CONDITIONING & COOLING TROLLEYS

The engines are off. The electronics are not.

Name: Mobile Air-Conditioning & Cooling Trolley
Brand: Neometrix

An aircraft on the ground has no ram air and no engine-driven cooling, but its avionics still have to run for checks, loading and pre-flight — and a vessel alongside with its own plant opened up has the same problem. Those boxes dump heat into a closed volume that is also sitting in the sun. So this is not comfort cooling: the trolley is sized on heat load, never on floor area, and it passes or fails on whether the bay stays below the temperature at which equipment derates. Two things then decide whether it works. The cold has to travel down a long insulated duct, so the machine is rated at the delivery end, not at its own outlet — a trolley that makes its number at the outlet and misses it at the aircraft has failed. And it has to start on whatever supply the apron actually offers, then survive being towed and left outdoors. Equipment of this class has been quoted across naval air-conditioning trolley and aircraft ground cooling trolley requirements; no delivered air-conditioning trolley is claimed — the class is engineered to order.

Enquire — cooling trolley Capability sheet (PDF)

Illustrative of the class — a mobile air-conditioning trolley standing on empty clean concrete hardstanding: a boxy mid-grey painted sheet-metal enclosure on a welded steel chassis with four small solid rubber-tyred road wheels, a long steel tow drawbar angled down at the front, wide bare-metal louvred grilles across one side and the top for condenser air, a recessed blank control panel with plain unmarked round gauges, a large circular flanged air outlet at the opposite end and a coiled grey insulated flexible duct stowed in a cradle on top, no people, nothing running and no readable markings

Fig · 01 A refrigeration plant that has to be towed, parked in the sun, and believed at the far end of a duct

Sized on

heat loadnot floor area

Rated at

the delivery endnot its own outlet

Runs on

whatever supply existsor its own diesel

Lives

towed and outdoorsvibration, salt, sun

Status

engineered to orderquoted class

ISO 9001 / 14001 Engineered to order Ground support equipment Performance proving & commissioning Noida · India

Overview

An aircraft is a cooled machine that stops cooling itself the moment it lands.

Everything about this class follows from that — and from the fact that the cold has to be carried somewhere before it counts.

Illustrative of the class — close view of the air delivery arrangement of a mobile cooling trolley: a large-diameter grey insulated flexible duct with visible helical reinforcing rings neatly coiled on a bare steel stowage cradle mounted on the side of the mid-grey painted enclosure, one end fitted with a plain circular bare-metal coupling ring with a bolted flange and lever latch, the duct running a short way across clean concrete, and the large circular flanged outlet on the trolley visible behind, no people, nothing running and no readable markings

Fig · 02 The least glamorous component on the machine, and the one that decides whether it meets its rating

In flight, the cooling is free. Ram air and engine bleed do the work, and the environmental control system has as much capacity as it needs. On the ground with the engines shut down, all of that stops — but the reason for cooling does not. Avionics have to be powered for functional checks, for loading and alignment, for troubleshooting and for pre-flight, and they dissipate essentially the same heat sitting still as they do at altitude. Now that heat has nowhere to go except into a sealed volume with a transparent roof, parked on a surface that is radiating back at it. The bay temperature climbs until something derates, throws a thermal fault, or simply fails earlier than it should have.

So the sizing question is thermal, not architectural. The load is the equipment dissipation, plus solar gain through skin and canopy, plus whatever fresh air the duty requires — and it is quite possible for a small volume to need far more cooling than a large one, because the electronics decide, not the cubic metres. A trolley chosen on the size of the space rather than on the heat in it will be comfortably wrong in either direction. The same reasoning applies alongside a jetty, where a compartment with its own plant opened up for maintenance still has equipment that must stay powered.

And then the cold has to arrive. It leaves the machine down a long flexible insulated duct, and that duct gains heat through its wall, drops pressure along its length, and often lies across hot tarmac on the way. All of that is real and none of it appears in a rating measured at the machine's own outlet. This is why the honest specification is written at the coupling: fan static pressure, duct insulation and a stated maximum length are consequences of it, and duct stowage becomes a design item rather than something coiled on the ground.

Equipment of this class has been quoted across naval air-conditioning trolley and aircraft ground cooling trolley requirements. No delivered air-conditioning trolley is claimed: the class is engineered to order, and the record is stated as it stands.

Load

Sized on the heat

Equipment, sun and fresh air — not the volume of the space.

Delivery

Proven at the coupling

Because the duct loss is part of the machine, not an allowance.

Reality

Weak supply, rough life

Starts on a long cable, then gets towed and left outdoors.

Architecture

Make the cold, get it down the duct, on whatever power is there.

The schematic follows the duty first — the load, the sun, the duct, and where the measurement is actually taken — then the four blocks behind it.

FIG · 03COOLING TROLLEY ARCHITECTURE · REFRIGERATION CIRCUIT / AIR HANDLING + DELIVERY / POWER, DRIVE + CONTROL / CHASSIS, MOBILITY + ENVIRONMENT

Fig · 03 Two ways to make cold — and choosing between them changes the whole machine

Arc · 01

Refrigeration Circuit

Compressor, condenser, evaporator, expansion — with capacity control, so a light load does not make it short-cycle.

Arc · 02

Air Handling & Delivery

Blower sized for duct static — insulated flexible duct, couplings, filtration and delivery-temperature control.

Arc · 03

Power, Drive & Control

Supply variants and the diesel option — starting against a weak board, protections, controls and indication.

Arc · 04

Chassis, Mobility & Environment

Drawbar, brakes, tyres, towing stability — weatherproofing, corrosion protection and vibration isolation.

Specifying a cooling trolley, or replacing units that miss their rating at the aircraft? Send the heat load or the equipment list, the delivery temperature required at the coupling, the duct length, the supply available and the applicable standard — a clause-by-clause compliance matrix within two working days · [email protected]

Send tender spec

Specifications

Sized on the heat, judged at the far end of the duct.

The parameters below describe the engineering approach. Refrigeration capacity and refrigerant selection, blower and static pressure, duct diameter, insulation and maximum length, supply arrangement and starting method, and chassis and towing design all follow from four givens: the heat load or equipment list, the delivery temperature required at the coupling, the supply actually available, and the applicable standard.

Illustrative of the class — the machinery bay of a mobile air-conditioning trolley seen with its side casing removed: a compact horizontal refrigeration compressor in mid-grey paint sitting on black rubber anti-vibration mounts, neat runs of bare copper refrigerant pipework with brazed joints and swept bends, a finned condenser coil block behind a bare metal guard, two plain grey electrical enclosures with completely blank covers and two small round gauges with blank white faces, all inside the welded steel chassis frame standing on clean concrete, no people, nothing running and no readable markings

Fig · 04 Brazed joints and anti-vibration mounts — a fixed plant needs neither, and this is why

Where these trolleys go wrong

Rated at the machine outlet rather than at the aircraft, so the duct loss never appears in the number and the unit is short in service with nobody able to say by how much. Sized on volume rather than heat load — the electronics and the solar gain are the load; the air is only the vehicle that carries it. No part-load capacity control, so on a light load the compressor short-cycles and the delivery temperature swings through exactly the band it was bought to hold. Designed for a clean supply, then nuisance-tripping on a weak board at the end of a long cable — which is the only supply it will ever actually see. A refrigeration circuit built like fixed plant, so towing vibration works the joints and it leaks refrigerant slowly for a year before anyone notices. And the duct treated as an accessory: no stowage, so it drags on tarmac, gets crushed by a tug, and becomes the first failure on an otherwise sound machine.

So the discipline runs the other way. The duty is established as a heat load from the equipment list before any capacity is chosen. Performance is specified and proven at the coupling, with duct length and insulation stated as part of the rating rather than left to the site. Capacity control is treated as a requirement, not an option, because part load is the normal condition. The electrical design assumes the worst credible supply and is checked for starting behaviour at the end of a long cable, with the diesel variant offered where no supply can be relied on at all. The refrigeration circuit is built for a vehicle — brazed joints in preference to flared, the compressor on designed mounts, pipework routed and clipped for movement. And the duct gets a cradle, because a component that is stowed properly is a component that survives.

Full specification — expand

System	Mobile air-conditioning & cooling trolley — refrigeration circuit, air handling & delivery, power, drive & control, chassis, mobility & environment
Governing Idea	Not comfort cooling. The duty is holding equipment below the temperature at which it derates or trips — with no ram air and no engine-driven cooling available
Sized On	Heat load — equipment dissipation plus solar gain plus the fresh-air load. Never on volume or floor area: the electronics decide, not the cubic metres
Rated At	The delivery end, not the machine's own outlet. The duct loss is part of the machine, not an allowance to be argued about later
Why The Duct Governs	Heat gain through its wall, pressure drop that consumes the fan, and a duct lying on hot tarmac — so it sets fan static pressure, insulation and a maximum stated length
Part Load	Capacity control is a requirement, not an option — part load is the normal condition, and without it the compressor short-cycles and the delivery temperature swings
Power	Designed for the worst credible supply — differing voltages and frequencies, long cables with real volt drop — and checked for starting behaviour at the end of that cable. Diesel prime mover where no supply can be relied on
Mechanical Duty	A towed vehicle — drawbar, brakes, tyres, lashing points, a centre of gravity that behaves under tow — left outdoors in sun, rain and salt air
Why Construction Differs	Continuous vibration and shock a fixed plant never sees: brazed joints in preference to flared, the compressor on designed anti-vibration mounts, pipework routed and clipped for movement
Two Ways To Make Cold	Vapour-compression with a refrigerant — efficient, compact, and what this class uses — versus air-cycle, which uses only air with no refrigerant at all. A different machine, not a variant, and the first decision to take
Heating	The same trolley is usually asked to deliver hot air in winter for exactly the same reason, so heating sits in the same box
Duct Handling	Stowage is a design item — an unstowed duct drags, is crushed, and becomes the first failure on an otherwise sound machine
The Split	The aircraft ground air-conditioning cart is the air-cycle machine — it makes cold from air with no refrigerant at all; this class is vapour-compression. Different physics, different duty, not variants of each other. The jet air starter trolley shares the apron and the drawbar but delivers a short, high-pressure blast to spin an engine; this delivers cold air continuously for hours. And the refrigeration system is a fixed installation sized once for a known space; this one has to make cold anywhere, on whatever supply exists, while being towed
Scope Boundary	Ours: trolley design & integration, heat-load sizing & delivery-end performance, refrigeration circuit design & vibration-tolerant construction, air handling & the duct and coupling arrangement, power scheme & starting behaviour, chassis, drawbar, braking & towing stability, weatherproofing & corrosion protection, controls & protections, installation, commissioning, performance proving at the delivery end, documentation, training, spares & AMC — including build to the customer's specification. Bought-in certified: compressors, motors and diesel prime movers, heat exchangers, refrigerant components and controls, tyres and braking components, instruments. The customer's: the aircraft or compartment, the supply available, the applicable standard and the acceptance programme
Status	Engineered to order — equipment of this class quoted across naval air-conditioning trolley and aircraft ground cooling trolley requirements; no delivered air-conditioning trolley is claimed

PDF · 1 page

Mobile Air-Conditioning & Cooling Trolley — Capability Sheet

Tender Response

Send heat load, delivery temperature, duct length & supply — compliance matrix in two working days

Variants

One principle, four trolleys.

What changes is where the power comes from, how hostile the environment is, and whether the same box has to heat as well as cool.

Var · 01

Electric Mobile Cooling Trolley

Where a supply exists — apron or jetty power, with starting behaviour designed for the far end of a long cable.

Var · 02

Diesel-Driven Self-Powered Trolley

Where none can be relied on — the machine brings its own prime mover, and the supply argument disappears.

Var · 03

Naval / Shipboard Trolley

Salt air and a tight footprint — corrosion protection, compact plan, and delivery through a hatch rather than to an airframe coupling.

Var · 04

Heating-and-Cooling Trolley

Both modes in one box — because winter presents the same problem from the other direction, to the same equipment.

Applications

Wherever equipment must stay powered and its own cooling is not running.

The duties that need conditioned air brought to them rather than built in.

A · 01Aircraft ground support on the apron

A · 02Vessels alongside & during refit

A · 03Equipment bay cooling during checks

A · 04Hangar & shelter spot cooling

A · 05Field shelters & mobile command posts

A · 06Standby cooling during plant maintenance

FAQ

Common questions.

Plain-language answers from the engineering team.

Q · 01 Why size on heat load rather than on the size of the space?

Because the space is not what is being cooled — the equipment in it is, and the two bear almost no relation to each other. A cooling duty is the sum of three things: the heat the equipment dissipates, which for powered avionics is substantial and essentially constant whether the aircraft is flying or parked; the solar gain through skin, canopy and transparencies, which on a sunlit apron can rival the equipment load and varies enormously with the airframe; and the fresh-air load, which is whatever outside air the duty requires, brought in at ambient and cooled to delivery temperature. None of those scale with volume. A compact bay stuffed with powered boxes under a clear canopy can need several times the capacity of a much larger, emptier compartment. Sizing on cubic metres is therefore a guess dressed as a calculation, and it fails in both directions: undersized units never hold temperature and run continuously at full load, while oversized ones short-cycle, swing the delivery temperature and cost more to buy and to tow. The honest starting point is an equipment list with dissipations, an assumption about solar condition, and a stated fresh-air requirement — and where a customer cannot supply that, establishing it is the first engineering task rather than something to be skipped.

Q · 02 Why insist on rating the machine at the coupling instead of at its outlet?

Because between the outlet and the aircraft there is a long flexible duct, and that duct is not a neutral pipe — it is a component that actively removes performance. Three things happen along it. It gains heat through its wall from ambient air and, worse, from the hot surface it is often lying on, so the air arrives warmer than it left. It drops pressure along its length and through every bend, which the blower has to overcome; if the fan was selected for free-air delivery, the actual flow will be well below the rating. And it is handled: dragged, kinked, occasionally crushed, each of which makes the first two worse. A rating quoted at the machine's own outlet quietly excludes all of this, which is why two units with identical headline figures can behave completely differently on the same apron. Specifying at the delivery end forces the honest conversation instead: the duct length and diameter become part of the specification, insulation is selected rather than assumed, and the blower is chosen for real static pressure. It also makes acceptance meaningful, because the test is then conducted where the air is actually used. The practical consequence is that a maximum duct length is stated — and if a site needs more, that is a design change, not a field decision.

Q · 03 Why is starting behaviour on a weak supply such a recurring problem?

Because the supply a cooling trolley actually gets is nothing like the supply a machine is usually designed against. It is fed from an apron or jetty outlet, often through a long trailing cable, sometimes through more than one connector, and frequently from a board that several other things are already using. The result is a supply with meaningful volt drop under load, and possibly a different voltage or frequency from the one the equipment was designed around. A refrigeration compressor draws a substantial starting current; on a stiff supply that is unremarkable, but at the end of a long cable it depresses the voltage further at the very moment the motor most needs it, which either stalls the start or trips the protection on the board — and the trolley gets a reputation for being unreliable when the machine itself is fine. So the electrical design has to assume the worst credible supply rather than a nominal one, and the starting method is chosen deliberately to limit inrush and to tolerate voltage that sags during the start. Where no supply can be relied on at all — a dispersed site, a field shelter, an apron with no serviceable outlet — the answer is the diesel-driven variant, which removes the argument entirely by bringing its own prime mover, at the cost of fuel, noise and maintenance.

Q · 04 How is the refrigeration circuit different from a fixed installation?

The thermodynamics are identical; the mechanical environment is not, and that is what changes the build. A fixed plant is bolted to a floor, and once commissioned its pipework never moves again. This machine is a towed vehicle. It is pulled across joints and potholes by a tug, sometimes faster than anyone intended, and everything inside it experiences that as continuous vibration with occasional shock. Refrigerant pipework is the vulnerable part, because a slow leak is not dramatic — capacity falls off gradually over months, nobody connects the two, and the unit is eventually written off as underperforming. So the construction is deliberately different: brazed joints in preference to flared or threaded ones wherever the design allows, because a brazed joint does not work loose; pipework routed with deliberate flexibility and clipped at intervals so vibration is not concentrated at a fitting; and the compressor on selected anti-vibration mounts rather than bolted rigidly to the chassis. The same logic extends outward — enclosure fasteners that stay done up, coil guards that survive handling, and a corrosion specification that assumes salt air and permanent outdoor storage rather than a plant room.

Q · 05 Vapour-compression or air-cycle — how do you choose?

They are two genuinely different machines that happen to deliver the same thing, and the choice is made first because everything else follows from it. Vapour-compression is the conventional route: a refrigerant is compressed, condensed, expanded and evaporated, and it is efficient and compact for the capacity it delivers. That efficiency is why it dominates: for most ground and shipboard duties it gives the most cooling per unit of size, weight and power, and its components are widely available and well understood. Its costs are that it contains a refrigerant, which must be contained, handled and eventually recovered, and that a slow leak degrades performance invisibly. Air-cycle takes the other path entirely: it compresses air, cools it, then expands it through a turbine to make it cold — so the working fluid is simply air and there is no refrigerant in the machine at all. It is less efficient, but nothing can leak that matters, there is nothing to recover, and it reaches low delivery temperatures readily. That is the machine our ground air-conditioning cart uses. Neither is a variant of the other — the compressor, the heat exchangers, the controls and the failure modes all differ — so the sensible order is to settle the cycle against the duty and the customer's position on refrigerant handling, and design from there.

Q · 06 What do you build, what is bought in — and what is claimed?

Divided honestly. What Neometrix provides: the trolley design and integration — deriving the machine from the heat load and the delivery requirement rather than from a catalogue; heat-load sizing and delivery-end performance, including the duct length, diameter and insulation that make the rating meaningful; the refrigeration circuit design and its vibration-tolerant construction, which is what separates a towed machine from a plant room; the air handling, duct and coupling arrangement with stowage designed rather than improvised; the power scheme and starting behaviour against the worst credible supply, or the diesel variant where none exists; the chassis, drawbar, braking and towing stability, plus weatherproofing and corrosion protection for permanent outdoor life; the controls and protections; and installation, commissioning, performance proving at the delivery end, documentation, training, spares and AMC — including build to the customer's own specification. What is bought-in certified: compressors, motors and diesel prime movers, heat exchangers, refrigerant components and controls, tyres and braking components, and instruments — proprietary products of established makers, integrated rather than imitated. What is the customer's: the aircraft or compartment, the supply available, the applicable standard and the acceptance programme. And the record, stated plainly: equipment of this class has been quoted across naval air-conditioning trolley and aircraft ground cooling trolley requirements, and no delivered air-conditioning trolley is claimed. The class is engineered to order, around the heat it has to remove.

↗

Cold from air, air to start, and cold that stays put.

Three neighbours — one shares the apron, one shares the physics, one shares neither.

↗ No refrigerant

Aircraft Ground Air-Conditioning Cart

Air-cycle — cold made from air itself. A different machine, not a variant.

↗ Same apron

Jet Air Starter Trolley

A short high-pressure blast to spin an engine — not hours of cold air.

↗ Fixed

Refrigeration System

Installed once for a known space — this one has to work anywhere.

Browse all Neometrix product lines.

Get a quotation

Send the heat load
and the duct length.

The projects desk replies within two working days with a clause-by-clause compliance matrix and a budgetary quotation. Write to [email protected] or use the form.

Enquire — cooling trolley Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED TO ORDER — MOBILE AIR-CONDITIONING & COOLING TROLLEYS SIZED ON HEAT LOAD · RATED AT THE DELIVERY END · BUILT TO BE TOWED ENGINEERED IN NOIDA · INDIA

The engines are off. The electronics are not.

An aircraft is a cooled machine that stops cooling itself the moment it lands.

Sized on the heat

Proven at the coupling

Weak supply, rough life

Make the cold, get it down the duct, on whatever power is there.

Refrigeration Circuit

Air Handling & Delivery

Power, Drive & Control

Chassis, Mobility & Environment

Sized on the heat, judged at the far end of the duct.

Where these trolleys go wrong

One principle, four trolleys.

Electric Mobile Cooling Trolley

Diesel-Driven Self-Powered Trolley

Naval / Shipboard Trolley

Heating-and-Cooling Trolley

Wherever equipment must stay powered and its own cooling is not running.

Common questions.

Cold from air, air to start, and cold that stays put.

Aircraft Ground Air-Conditioning Cart

Jet Air Starter Trolley

Refrigeration System

Send the heat load
and the duct length.

Similar Products

Share This Page

The engines are off. The electronics are not.

An aircraft is a cooled machine that stops cooling itself the moment it lands.

Sized on the heat

Proven at the coupling

Weak supply, rough life

Make the cold, get it down the duct, on whatever power is there.

Refrigeration Circuit

Air Handling & Delivery

Power, Drive & Control

Chassis, Mobility & Environment

Sized on the heat, judged at the far end of the duct.

Where these trolleys go wrong

One principle, four trolleys.

Electric Mobile Cooling Trolley

Diesel-Driven Self-Powered Trolley

Naval / Shipboard Trolley

Heating-and-Cooling Trolley

Wherever equipment must stay powered and its own cooling is not running.

Common questions.

Cold from air, air to start, and cold that stays put.

Aircraft Ground Air-Conditioning Cart

Jet Air Starter Trolley

Refrigeration System

Send the heat loadand the duct length.

Similar Products

Share This Page

Send the heat load
and the duct length.