leversole Posted November 27, 2010 Share Posted November 27, 2010 Wondering what this is? One line comes from a service port on the treadle valve, the other goes to the column mounted trailer brake lever, and it has the brake switch. All of the diagrams I have show the column lever gets full air from the tank. Why would the trailer brake test valve get air only when the brake pedal is pressed? Confused...Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/ Share on other sites More sharing options...
hatcity Posted November 27, 2010 Share Posted November 27, 2010 Lever on the column is a trolley brake. Only works thr trailer brakes. Treadle works truck and trailer brakes. When you pull on the trolley brake, the brake lites "should" come on-thus the switch.Trolley brake was used as a parking brake, but could help slow you just a bit if needed. Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67459 Share on other sites More sharing options...
speedy Posted November 27, 2010 Share Posted November 27, 2010 (edited) Lever on the column is a trolley brake. Only works thr trailer brakes. Treadle works truck and trailer brakes. When you pull on the trolley brake, the brake lites "should" come on-thus the switch.Trolley brake was used as a parking brake, but could help slow you just a bit if needed.The 'Trolly' brake lever (We call it the trailer brake or 'spike'), should NEVER be used as a parking brake. It can work it's way off by vibration of the engine or even simply ease off on it's own. It is not to be relied on for parking - use the buttons on the dash. That being said, it's main use is for braking in slippery conditions, it will help keep a tractor-trailer straight - you can also apply the pedal brake and override it to apply even more braking pressure to the trailer - this takes some experience/practice.It can also be used to back under a low trailer that doesn't have spring brakes, back up to the trailer, connect your air lines, pull the spike to apply the trailer brakes and then drive the truck under while the 5th wheel lifts the trailer. Edited November 27, 2010 by speedy Quote Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67462 Share on other sites More sharing options...
hatcity Posted November 27, 2010 Share Posted November 27, 2010 The 'Trolly' brake lever (We call it the trailer brake or 'spike'), should NEVER be used as a parking brake. It can work it's way off by vibration of the engine or even simply ease off on it's own. It is not to be relied on for parking - use the buttons on the dash. That being said, it's main use is for braking in slippery conditions, it will help keep a tractor-trailer straight - you can also apply the pedal brake and override it to apply even more braking pressure to the trailer - this takes some experience/practice.It can also be used to back under a low trailer that doesn't have spring brakes, back up to the trailer, connect your air lines, pull the spike to apply the trailer brakes and then drive the truck under while the 5th wheel lifts the trailer.Don't know if his truck has all the air buttons. 1965. Trailers from that era, did they have spring brakes? Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67464 Share on other sites More sharing options...
Rob Posted November 27, 2010 Share Posted November 27, 2010 Wondering what this is? One line comes from a service port on the treadle valve, the other goes to the column mounted trailer brake lever, and it has the brake switch. All of the diagrams I have show the column lever gets full air from the tank. Why would the trailer brake test valve get air only when the brake pedal is pressed? Confused...ThanksLooks like a check valve.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67474 Share on other sites More sharing options...
CML Service Posted November 27, 2010 Share Posted November 27, 2010 Wondering what this is? One line comes from a service port on the treadle valve, the other goes to the column mounted trailer brake lever, and it has the brake switch. All of the diagrams I have show the column lever gets full air from the tank. Why would the trailer brake test valve get air only when the brake pedal is pressed? Confused...ThanksIt is a double check valve. Sends air to tractor protector valve. Connected to trolley and treadle. In a proper trailer hookup air lines are connected to trailer before trailer tips fifth wheel. Then trailer brakes are applied with trolley lever. As said before old trailers didn't have spring brakes. So without applying air brakes you could wind up chasing the trailer for quite a distance. Quote Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67507 Share on other sites More sharing options...
leversole Posted November 27, 2010 Author Share Posted November 27, 2010 Thanks all...The brake switch would only work with a full and lengthy application of brakes.So for now,I bypassed this check valve and put on a new brake switch, everything groovy now Quote Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67518 Share on other sites More sharing options...
David Posted November 27, 2010 Share Posted November 27, 2010 I though the main use of the Trolly was for when you were pulling someone else's trailer, you could wear out their brakes and save yours. Quote Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67545 Share on other sites More sharing options...
Rob Posted November 27, 2010 Share Posted November 27, 2010 I though the main use of the Trolly was for when you were pulling someone else's trailer, you could wear out their brakes and save yours.Works good with electric trailer brakes too.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67546 Share on other sites More sharing options...
HK Trucking Posted November 28, 2010 Share Posted November 28, 2010 That's a combination double check valve/stoplight switch. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67596 Share on other sites More sharing options...
leversole Posted November 28, 2010 Author Share Posted November 28, 2010 That's a combination double check valve/stoplight switch.That makes the most sense...as you would want the trolley valve and the treadle to both actuate the brake light...The switch was sluggish is why I replaced it...it is probably full of oil!Thanks all Quote Link to comment https://www.bigmacktrucks.com/topic/16637-mystery-item/#findComment-67609 Share on other sites More sharing options...
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