This site has proved so good in the past and I know there is a wealth of expertise out there so here goes. Sorry if I appear to be upsetting others.
I know this is not the correct site for truck matters and I have to pick a make and model but I am looking for help with a Leyland Roadrunner with a jammed parking brake. Austin Rover seemed the most appropriate, sorry. Any site suggestions (www???) or other help will be appreciated. Thanks.
No need to apologise for upsetting others ! - I'll leave it under the Austin Rover tag for now and ask the site designer to add Leyland Trucks to the Drop Down Menu.
Edited by Pugugly on 25/09/2008 at 21:46
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Is it air. air over hydraulic, or hydraulic brake system ?
From my memory, its air ?
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Thanks for the reply. The truck is a Roadrunner horsebox with a demountable body. The brakes are: footbrake, hydraulic with air assistance, parking brake is air only to large spring loaded piston in centre of chassis. There is air pressure in the tanks. 3 tanks on N/S of chassis behind cab. Dials on dash and alarm show pressure build up and alarm stops. drain on tanks shows little water. All tanks have presure as depressing pins on tank bases blows air out at high pressure. No air in pipes to hand brake control, have disconnected all and nothing there. No air in pipe as connected to air brake release cylinder. Disconnected pipe and no air. Had to move truck as in the way of others. Tried to back off cable adjusters but one nut siezed on thread so had to remove fulcrum pin and drive out with drift. Drove truck to safe area. Placed in gear, propped wheels and retained keys so no one can drive until sorted. Demountable body has air jacks on separate cylinder which works with air switch and front and rear selector on chassis by drivers seat. This has worked well in the past to remove box but is it interlocked with parking brake, preventing truck moving whilst body is being jacked? Driver reports parking light flickered on/off but parking brake worked on last trip but after parking and 2 days later parking brake locked on. Parking light is on constantly now. Any help from truck mechanics would be helpful. Paul
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3 possibilities I think;
- a stuck circuit protection valve (although, this should prevent the relevant tank being filled)
- a stuck interlock valve (if fitted). This valve prevents the spring brake being released if the air pressure is built up with the handbrake in the off position, where the vehicle would suddenly roll away as the spring brake is pushed off by the building air pressure. Drain the system down, and restart with the brake on.
- an interlock valve designed to prevent drive away while demounting the body has stuck, or the body is not fully home. I think this is the most likely avenue for exploration.
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Thanks yorkiebar and Number_Cruncher for your advise. Not sure where to look for these valves but I will try the drain down and recharge with air brake on first. With the controls for the air jacks treading pipes everywhere that interlock could be a problem. If I can sort it I will get it to a more accessable location and get the system fully checked out although finding people who know about this age of truck is a bit of a problem. The brakes siezed up last winter and no one could really tell me where to put the air brake anti-freeze. There are 2 plastic bottles by the air tanks, one says anti-freeze in several languages and a lower bottle is broken but no one could say for sure what it was used for. It passed its inspection at the local truck MOT station in that state and no one mentioned it. Getting parts for it is very difficult now. The local Leyland DAF parts supplier sold me the last alternater belt tension pulley they had in their main store department or so they told me. The truck is stuck out in the wilds at the moment and getting someone out there or having the truck recovered is not really an option. Did a clutch change and welded up the front cab hinges a few months ago so I do know most of the truck well. Clutch slave cylinder was leaking into the bell housing and loosing fluid at an alarming rate. The truck was recovered by a garage and they changed the master cylinder but this did not solve the problem so I was called in. I seemed to be the caretaker for this vehicle now. The problem with the brakes has got me stumped has I'm used to large vans rather than small trucks.
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sounds like relay valve stuck to me . on crossmember above propshaft centre bearing if i remember correctly. Just got rid of our last one , ran 4 Daf 45s for 10 years so know these little beauties inside out.
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>>sounds like relay valve stuck to me
Normally, I would agree - but, if the relay valve sticks, how does this stop air getting to the hand brake valve as the OP describes?
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Thanks for the help guys. I am going to have a look at the truck this weekend, time permitting. I will look for the valves you mentioned and try the drain and recharge suggested earlier. I'll let you know how I get on. Watch this space. Cheers
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