Keep Your Cool and Carry On

An integral and often overlooked part of any powertrain system is the cooling and lubricating circuits and componentry.
Lubricants must be maintained within a predetermined temperature window in order to perform their dual tasks of lubricating and cooling moving parts. This is even more critical in a hydraulic system where the fluid is also the prime mover.

To achieve this and to maintain critical tolerances between moving items the mass of the powertrain structure must be kept at a stable temperature, regardless of ambient conditions. This is the responsibility of the machines cooling system.

To complicate matters, modern technology is such that the mix of materials used may have vastly different thermal characteristics. An example of this can be found in most late model automotive designs which use plastic tanks and aluminium cores in cooler construction. The stress caused by vibration and heat, tax the durability of such designs, often to the very limit. These materials also make service and repair difficult, usually impossible. Typically replacement is the only remedy.

When reliability is critical, the selection of pieces and their design becomes a significant factor. These applications are usually more remote than automotive ones. Productivity/profitability of an operation rely heavily upon the dependability of the equipment in use.

Dust, debris, vibration and other elements are common to most mobile equipment environments. They are also enemies to efficient cooling and longevity of cooling systems and components. Maintaining adequate air flow through a cooler is the main obstacle to maintaining efficient heat dissipation. Moisture and bitumen in dust adds to the problem making the particulate rigorously adhere to the gilling, accumulating and inhibiting heat transfer.

A traditional soldered, folded fin core will clog quickly, and depending on the composition of the dust may not be cleanable in-situ. Likewise debris and vibration may compromise the core and surrounding structure requiring removal and replacement.

The cooling system design may be dictated by initial cost and may not consider the true life-cycle costs of a particular choice in design. Just like selecting the correct coolant, oil or tires for your fleet, life-cycle costs must balance an item’s price in order to make a value judgement on a cooler’s suitability.

Recently a paving contractor had issues with their CMI milling machine radiator clogging due to bitumen dust. Steam cleaning provided modest relief and the coolers were regularly removed/replaced during the working season in order to ensure productivity.

A solution in the form of an individually, shock-mounted, “V” tube core radiator from MESABI flexible core heat exchangers was presented to this contractor.

The “V” tubes provide a free passage for dust and debris without reducing cooling efficiency. The individual rubber-mounted tubes eliminate fracturing of solder joints from high vibration as experienced when milling or crushing RAP. Maintenance has been reduced to a more normal interval and does not impact daily operation in the working season.

Depending on the application these coolers and radiators are available in varioussizes, configurations and materials (ie. copper, aluminium, brass etc.) and come as standard on many OEM-branded models such as Caterpillar, Komatsu, Liebherr and Atlas-Copco. They can be fitted aftermarket and are also readily serviceable and field repairable making them ideal for a variety of applications and customers.

The cooling core can be further enhanced by the type, pitch and drive of the fans used with them. Variable pitch and reversible fans are available for most applications and enhance the ability to keep the core free of debris as well as reduce fuel costs by matching blade pitch to rpm.

Most cooling systems are designed with “worst case” situations as their backdrop. This means that often the fan size and pitch may be less efficient when idling or operating at reduced capacity. By manipulating the pitch, the airflow through the core can be maintained, but the horsepower requirement is reduced. This results in quieter and more fuel efficient operation. Often the ability to reverse the fan can permit the automatic removal of larger debris (leaves, paper, etc.) from the face of the core.

Cooling systems are deceptively simple so generally do not receive the specialist attention they deserve. Leak and pressure testing of coolers requires experience and equipment most general repair shops lack. To get the most out of your equipment and maximize the life of its cooling system, always consult a specialist for advice and repairs.

Source: Armand Signori Auto Radiateur Inc.

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