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Any brand log trucks

camptramp

camptramp

Senior Member
Joined
Aug 13, 2013
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6,303
Location
The warm land on Vancuver Island
Occupation
Retired Logger Retired Part time pebble hauler
Roy Johnson Collection In 1980 I was working with our old friend Roy Johnson at BCFP Renfrew Division . One evening I was at his home visiting , when he brought out a photo album from the 1950's . After I had looked through it I borrowed a couple of pictures and had reprints made . I regret I didn't have the whole photo album copied . Roy was a colourful character lots of stories , and there was no doubt true . Tough as nails with a heart of gold . BCFP Renfrew division had several Northwest Grade Shovels converted to log loaders they were all a little bit different , they had four Washington loaders two TL6's that were different from factory and and two TL15's a early 1950's and a 1965 that again were different , a early 1970's American 7220 and several Skagit , Tyee and Madill Yarders . Roy could get on any one of them and run them with ease as the Camp Spare Operator . The picture is of a load he loaded with either a Loading Pot Heal Boom on a wooden Spar Tree or with the #95 a Washington TL15 Track Loader on tongs . Scan17.jpg
 
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Birken Vogt

Charter Member
Joined
Nov 30, 2003
Messages
5,340
Location
Grass Valley, Ca
I see. So in order to get the same force, if I am doing the math right, for a type 30 chamber x 90 psi that would be 2,700 lbs force which would be 14 psi vacuum on a 193 sq. inch chamber or 16 inches diameter. Or maybe a longer slack adjuster or different ramp rate on the cam head. Or just accept brakes that did not work as well.

Probably all of the above.

Did the brakes have a long application time getting vacuum back to the chambers? Was there a vacuum reservoir and relay valves? I could see a loss of force at high elevation where the air pressure was lower.
 
John C.

John C.

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Joined
Jun 11, 2007
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12,870
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Northwest
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Machinery & Equipment Appraiser
What I remember about vacuum brakes was a simple juice brake with a big vacuum amplifier chamber on the master cylinder.
 
DMiller

DMiller

Senior Member
Joined
Feb 21, 2010
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16,644
Location
Hermann, Missouri
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Cheap "old" Geezer
Were both
Vacuum chambers were what started with then upped the game to vac applied hydraulics, not much better.
Relied upon Engine vacuum no pumps so volume of use vanished in a heartbeat.

Have only seen and worked antiques both styles.
 
Truck Shop

Truck Shop

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Joined
Dec 7, 2015
Messages
17,156
Location
WWW.
Birken Vogt said:
I see. So in order to get the same force, if I am doing the math right, for a type 30 chamber x 90 psi that would be 2,700 lbs force which would be 14 psi vacuum on a 193 sq. inch chamber or 16 inches diameter. Or maybe a longer slack adjuster or different ramp rate on the cam head. Or just accept brakes that did not work as well.

Probably all of the above.

Did the brakes have a long application time getting vacuum back to the chambers? Was there a vacuum reservoir and relay valves? I could see a loss of force at high elevation where the air pressure was lower.
Click to expand...

Your math is pretty close-The combination of a large chamber plus a longer slack arm to cam gave the braking
force till vacuum ran dry. I changed out a two axle tilt bed equipment trailer 20 years ago from vacuum to air.
It was straight forward-simple. Swapped s-cams from side to side, welded air chamber mounts to axle, mounted
cans and slacks and used a FF2 valve. Used the vacuum reservoir for air tank.
 
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