Prime Mover Magazine


More than motor city

More than motor city

Detroit today means more than making engines. The company has developed an extensive range of modern components engineered and manufactured at its own premises. Prime Mover recently walked down the production line and came away rather impressed.

At the 3.2 million square foot facility in the city of its namesake, Detroit, Michigan, the Detroit company manufacturers major powertrain components including the range of Detroit Diesel engines as well as driveline components including the DT12 automated manual transmission and Detroit rear and front axles.

Initially owned and operated by General Motors the plant commenced production in 1938 and has been building truck engines since 1955.

The facility has undergone several multi-million dollar upgrades since the beginning of the 21st century and the organisation was rebranded as Detroit in 2011 as it had become more than just an engine manufacturer.

Production of the first of the DD platforms began in 2008 with the DD15 and the facility currently produces the DD13, DD15 and DD16 heavy duty units and the DD5 and DD8 light duty engines. Since it began operations more than eighty years ago Detroit has produced more than five million engines including one million during the past 20 years.

The current annual production amounts to 110,000 heavy duty engines, 10,000 medium duty engines and 45,000 transmissions. Detroit was purchased by Daimler in 2000 and has since been a key factor in the global developments and manufacture of Daimler’s major driveline components.

Product engineering and testing are under the same roof, as is the Detroit national customer call centre, creating a situation which streamlines the process from product inception all the way to aftermarket support.

All displacements of the Detroit engines have similar designs and construction which incorporates wet cylinder liners, cast engine blocks and one piece cylinder heads. Extensive webbing on the Detroit blocks is used for strength as well as reduction in noise and vibration.

Raw engine block and cylinder head castings are produced in South Africa and are then machined at the Detroit facility. Improvements in design are such that only 35 pounds of material needs to be removed from a DD15 block compared with the 150 pounds that used to be machined off a block for a Series 60 engine.

It takes around four hours for an engine to be processed down the line, and each is subjected to rigorous inspections at five ‘quality gates’ as more components are added. Torque tools are used extensively, not just on bearing and head bolts and every bolt and nut associated with the fuel rails is double checked. The aim is for each shift to produce 163 units.

Every engine is hot run tested on one of the 42 Dynometer prior to being shipped. At the Daimler truck plant in Charlotte North Carolina the engines are retested after installation into Freightliner and Western Star trucks to ensure there are no issues and to confirm power and torque ratings.

An increasing range of components are being manufactured ‘in-house’ to ensure quality and maximise production efficiencies.

Turbochargers used to be either the number one or two components subject of warranty claims. After two years of development the turbos began being produced at the plant in 2015 using a Daimler design identical to the Mannheim units used on Daimler truck engines in Europe.

Around 85,000 complete turbos are manufactured each year at the Detroit plant and rotor components are also exported to be used by Mannheim.

The turbo shafts have a tolerance of just six microns and bar codes and data matrix stamps ensure the aerospace-like quality which has resulted in drastic reductions in any turbo problems associated with Detroit engines. Turbocharger testing involves shaft speeds of up to 405,000 rpm. The use of the proprietary asymmetric turbo reduces weight and complexity plus delivers improved performance with sustainable reliability.

Behind the products are the people who make them and there is a palpable evidence of pride on the shop floor. The turbo division is a great example where there are nine employees dedicated to producing the turbos and all are qualified for each other’s roles.

Despite its massive size the overall facility shows a commitment to energy efficiency and environmental stewardship. Since 2008, the factory’s energy consumption has decreased by 48 per cent, while at the same time production has increased significantly. LED lighting is used extensively, and the facility-wide recycling program involves recycling or reusing items such as component packaging.

The most recent developments of Detroit engines such as the DD13 have focused on delivering a long flat torque curve to provide the driveability and fuel efficiency associated with engine down-speeding.

This has resulted in the DD13’s ability to deliver 90 per cent of its peak torque in just 1.5 seconds whereas in the same time a competitor’s engine will only be at 50 per cent. Factors contributing to this improved performance include the use of the non-waste gated turbo and low inertia camshafts.

As an adjunct to the power, the engine’s retardation braking capabilities have been enhanced with the improved ‘Jake’ engine brake which is integrated into the camshafts rather than sitting on top of the rocker arms.

This design change provides three stages of engine braking and is much quieter in operation.

Lifetime servicing is enhanced by the location of most key maintenance components above chassis rail for direct access which results in less service time and improved heat dissipation.

The larger capacity of the sump helps extend oil drain intervals as does the maintenance free crankcase breather which is a closed system and returns oil to sump. The DT12 automated transmission has been a success story for Detroit with 45,000 being produced at the facility annually.

The DT12 has well-recognised capabilities and its contributions to efficiencies begins in the basic architecture that utilises an alloy case and two gear shafts instead of three to significantly reduce weight.

Rear axles are another area where Detroit has pursued efficiencies which complement the down-speeding of the engines, and final drive ratios of 2.0:1 or 1.9:1 are becoming the norm, with even lower numerical ratios currently being assessed and likely to enter production soon.

The Detroit steer axles may not be as complex as engines or transmissions, yet they are a vital component of modern trucks. The Detroit front axles feature Torrington bearings to handle the thrust forces and to provide a long life of smooth steering.

For decades the terms ‘Detroit Diesel’ or ‘GM’ were commonly associated with the supercharged two stroke engines which the company produced for under GM’s ownership.

The modern ‘Detroits’ continue to derive some of their heritage from those venerable green painted icons that were a mainstay of truck and bus engines for decades.

The North American manufacturer’s and Daimler’s inputs, since 2000, today deliver a range of modern major driveline components that are able to operate seamlessly together regardless of the brand of vehicle they are fitted to.

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