Machine Design

Looking Back 6/14/2012

10 YEARS AGO — 2002
Cooling duct gives pistons longer life: High-ignition pressure and specific output of direct-injection diesel engines place heavy mechanical and thermal loads on pistons. Pistons with conventional salt-core cooling ducts often cannot withstand these loads.

Mahle Inc., Morristown, Tenn., has developed a piston with a cooled ring carrier formed by a steel plate welded directly onto the carrier. By cooling the piston, areas subject to high thermal load (the first groove and cavity perimeter) can handle higher loads, giving the pistons a longer running life. According to the company, comparative finite-element calculations on passenger vehicles show this technology lowers the temperature at the bottom of the first groove by approximately 50°C.

30 YEARS AGO — 1982
Humvee prototype to Army: The first of 11 prototype Humvees produced by Teledyne Continental Motors has been delivered to the Army for testing. TCM, Chrysler, and AM General are competing for the Humvee contract. In December, the Army is expected to start buying 53,000 of the vehicles configured as weapon carriers, ambulances, and utility vehicles. In the TCM version, the engine is an International Harvester 6.9-liter V8 diesel rated at 170 hp at 3,000 rpm. It delivers 310 lb-ft of torque at 2,000 rpm. Top speed of the vehicle is 70 mph, and speed on a 60% grade (low gear) is 10.6 mph.

50 YEARS AGO — 1962
Inaudible impulses, on one track of a two-track magnetic tape, change pictures in exact predetermined relation to the sound in this slide or filmstrip projector. During playback, the lowfrequency impulses are detected by a sensitive transistorized relay circuit, which actuates a solenoid to change the picture. The 500-W Synchro- Mat IV measures 10 × 13 × 17½ in. and weighs 37 lb. The projector is built by Synchro-Mat Equipment Corp., Jackson, Mich.

© 2012 Penton Media, Inc.

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