Nusbaum Farms LLC Bellfountain, OR | *Copied from www.mrsharkey.com*
During his 1931 cross country trip to promote diesel engines in trucks, Clessie Cummins and his crew almost died during a descent down Cajon Pass on old US66 in California. Their brakes overheated and failed and the truck ended up nearly crashing.
"About dusk on the fifth day, we reached the top of Cajon Pass west of Barstow, California. Before retiring to the sleeping compartment, Dave had warned me against this thirty-five-mile stretch of mountainous down-grade. ‘Wake up Ford and me when you get to Kayhone Pass,’ I had understood him to say, ‘I don’t want to be in this box when you start down that twister with the kind of brakes we’ve got.’ I had heard but not seen, my Spanish being nonexistent, the word Cajon failed to register when the sign appeared. Soon, however, I realized my error. The brakes wouldn’t hold. Now running in third gear, I tried desperately to get into a lower speed. Nothing doing. I saw I would just have to ride it out. Well down the long grade by now,I suddenly saw something moving across the road ahead. There was a long dark shadow and then a red glow flared in the sky. I realized with new alarm that a freight train was cutting across our path. The truck roared on. Dave and Ford screamed bloody murder in the compartment behind me. And I clung to that steering wheel like a madman. Had Mack Sennett been on hand with a movie camera, he would have gotten enough footage for one of his famous Keystone Kops features. As we raced inexorably toward the crossing and doom, the train’s caboose loomed out of the darkness. Its red lights cleared the highway just as we reached the tracks. We had escaped certain death by inches." - Clessie Cummins
Clessie knew that the engine already provided some compression braking on it's own, but felt that there must be a way to amplify that compression ability. He vowed to somehow make his engines work downhill just as well as they did uphill. He shelved the idea for the next 20 years and in 1955 started working on the idea. He was already retired from Cummins but that didn't stop him from coming up with new ideas. With his son Lyle and a machinist friend named Ray Hansen, he formed CENTCO (Cummins Enterprises Company), which was little more than Clessie's think tank in the basement of his home. They finally figured out that it was indeed possible to amplify the braking ability of the engine but were unable to come up with a way to do it that would follow the engine's timing.
In 1957 during a sleepless night in a Phoenix, AZ motel room, Clessie came up with the right idea. The camshaft on the Cummins N series, had 3 cams, one to open the intake valves, one to open the exhaust valves and one to activate the fuel injector plunger. A mechanism on the engine would cause the fuel injector cam to actually activate the exhaust valve at injection time, so instead of injecting fuel, the compressed air would be released. Without the combustion of fuel in the cylinder to create power, the engine was turned into a power robbing air compressor. Clessie filed his patent in shortly thereafter.
The first vehicle equipped with a CENTCO designed compression brake was a 1955 GMC Suburban Carryall repowered with a Cummins JN-6 engine. The vehicle had to be extensively modified to handle the large 401 cubic inch engine. Downhill tests were encouraging. The Suburban, weighing in at 6,500 lbs, was able to slow from governed speed (2,500 rpm) to idle speed in 200 yards on a 30% grade using nothing but the engine brake.
The Cummins NH series engines were very popular among the trucking industry and CENTCO developed one to fit, they used the N series marine engines on Clessies yacht as test mules. They simulated downhill braking situations using 4 of the cylinders to power the other two.
But they needed more testing, so in 1959 they equipped an Cummins NH powered truck owned by Sheldon Oil Company of Suisun, California. The truck was piloted by Bill Hill, an 18 year veteran truck driver. The test run was on US50 outside of Lake Tahoe. Mr. Hill was so impressed with the performance he stated he never wanted to drive another truck unless it was equipped with Clessie's engine brake.
Due to a contractual agreement, CENTCO was required to first present their ideas to their parent company Cummins. Cummins failed to see any promise in the idea and passed on it. All the other major diesel engine makers of the time passed as well.
Now here's where things take an interesting turn. Clessie's nephew Don was set up on a blind date with Roberta Englund, the daughter of Bob Englund, the Vice President of Jacobs Manufacturing Company. Don and Roberta hit it off and eventually married. Bob was introduced to Clessie and Lyle through Don's father Delosse Cummins. The brass at Jacobs Manufacturing, which specialized in drill chucks, was looking to diversify. Through Bob Englund, they caught wind of the compression brake idea, they thought it might be a wise investment. By 1961, the first compression brakes for the Cummins NH series engine were available commercially through Jacobs and the "Jake brake" was born.
*End of copied text*
One of the most important inventions in trucking, IMHO.
-Orin
Edited by Orin 12/22/2012 22:38
|
jakes on semis good or bad?
