Trailer Talk

A Fruehauf Lowboy Carried Palomar Observatory's Mirror

At 20 feet in diameter and weighing 28,000 pounds, the load was big, heavy and priceless.

June 17, 2015

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A Caltech engineer monitors the move from atop the boxed mirror that's borne by a Fruehauf lowboy and jeep trailer. Sterling tractors pull and push. Photo via Fruehauf Trailer Historical Society
A Caltech engineer monitors the move from atop the boxed mirror that's borne by a Fruehauf lowboy and jeep trailer. Sterling tractors pull and push. Photo via Fruehauf Trailer Historical Society

While researching a future article about the old Fruehauf Trailer Co., I rediscovered the story of the hauling of a piece of large, fragile and precious cargo in southern California almost 68 years ago. It was the circular glass mirror used in the Mount Palomar Observatory’s 200-inch telescope in San Diego County.

In November 1947 it moved on a Fruehauf lowboy trailer from the California Institute of Technology's campus in Pasadena, where it was precisely ground using special machinery, on a circuitous 160-mile route to the remote mountain top. I lived not far from Palomar on the occasion of the hauling job’s 50th anniversary in ’97, and recall a newspaper feature article about it.

An intriguing consideration was security, because threats had been made against it. Religious fanatics viewed the science that would peer into the heavens as an affront to God, the revealer of all truths. They talked of sabotaging the effort, but nothing like that happened.

What did transpire was a meticulously planned two-day journey -- four, if we count the time easing the load out of Caltech's shop -- involving Belyea Truck Co. and Pacific Crane & Rigging. Support vehicles, California Highway Patrol motorcycle escorts, and cars bearing press reporters and photographers moved with it, and thousands of people lined the route to watch.

Everything had been carefully surveyed and measured, bridges strengthened, and the movement closely monitored by a nervous Caltech engineer.

The trucking firms’ proprietor, Jack Belyea, prepared the lowboy and an intermediate “jeep” trailer to spread the weight of the glass disc and its steel container over 42 wheels. The load and trailers together weighed 60 tons, according to a tale on www.SingingWheels.com, the website of the Fruehauf Trailer Historical Society (current endeavors of Ruth Fruehauf, granddaughter of founder August Fruehauf).

Fruehauf Trailer created a special ad to proclaim its role in the move. Photo via Fruehauf Trailer Historical Society
Fruehauf Trailer created a special ad to proclaim its role in the move. Photo via Fruehauf Trailer Historical Society

Sterling truck-tractors powered by Cummins diesels pulled and pushed the big, heavy load, and a third Sterling joined in on steep grades. The first day got the caravan 123 miles to Escondido, where it paused for the night. A meteorologist had predicted clear weather for the trip. But, says an account by the San Diego Historical Society, it began drizzling that night. Then:

“By the next morning, the visibility was marginal. The official weather reports said it was 150 feet; workmen remembered it as 50 feet. For the climb up the mountain, the lead tractor was joined by two other tractors pushing the trailer from behind. The Highway to the Stars [the road to the observatory] had been designed and built for this cargo, engineered so that the crated disc would just clear each turn. There was no room for a Highway Patrol escort.

“[Caltech engineer] Byron Hill met the cargo at the bottom of the mountain and rode up standing on top of the crated disc, shouting directions to men who walked alongside and ahead of the tractors and trailer to mark the edges of the road.

"The cold rain turned to a mixture of sleet, ice, and snow. The visibility was so poor the drivers of the second and third tractors couldn't see the puffs of exhaust from the first tractor; they coordinated their gearshifts on the grades by listening for the sounds of the engine and transmission of the lead tractor.

“Steadily, the three tractors climbed the grade with their priceless cargo... Once the tractors started up the mountain, there was no stopping, only the slow steady climb from the desert floor to the mile-high top of the mountain.

"It was 11 a.m., four hours ahead of schedule, when the lead tractor rolled through the observatory gate. After a break for coffee to relax taut nerves, Lloyd Green, a driver with 25 years’ experience at Belyea, backed the trailer through the doorway in the side of the dome that had been waiting for a decade for the priceless mirror.”

That truck haul in 1947 was the climax of a project that began with an announcement in October 1928, followed by unprecidented engineering and design work into 1934. It took form with the pouring of 20 tons of molten Pyrex glass at the Corning Glass Works in upstate New York – twice, as the first casting spoiled – and carrying of the circular glass “blank” by rail across the country in 1936 – a story in itself (http://www.journeytopalomar.org/palomar.html).

At Pasadena, the load was trucked a short distance to Caltech where special machinery would spend 11 years grinding its surface to a convex, parabolic shape with accuracy to 2 millionths of an inch.

Some 10,000 pounds of glass were ground and polished off, leaving the disc's weight at 14 tons, plus an aluminum coating to complete the mirror. Gears for the mirror’s adjusting mechanism at the observatory were also machined, and a support structure, the observatory building, and a road to it were constructed at Palomar Mountain.  

The large mirror and its telescope reside with two smaller instruments inside the dome of Palomar Observatory in northern San Diego County. Photo via Caltech
The large mirror and its telescope reside with two smaller instruments inside the dome of Palomar Observatory in northern San Diego County. Photo via Caltech

Most phases of the project got intense publicity, especially during the Great Depression, when people looked for exciting news that gave them escape from dreary reality and hope for better times. The attack on Pearl Harbor halted work until the war’s end. And two more years would be needed to complete the intricate installation and painstaking adjustments needed to make the device operable.

Massive mirror was placed on a supporting and adjustment structure at the observatory. Photo via Fruehauf Trailer Historical Society 
Massive mirror was placed on a supporting and adjustment structure at the observatory. Photo via Fruehauf Trailer Historical Society

The Hale Telescope was the largest instrument of its kind in the world until 1993. It found previously unseen wonders in the universe, and its key element, plus all supporting equipment, got to Palomar by truck.

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Author Bio

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Tom Berg

Senior Contributing Editor

Journalist since 1965, truck writer and editor since 1978. CDL-qualified; conducts road tests on new heavy-, medium- and light-duty tractors and trucks. Specializes in vocational and hybrid vehicles.

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