Parked at Exeter services one night last week, arrived about 7pm. Anyway later on I was half watching Grand Designs/half snoozing on the bunk about 9.30pm, when a loud bang from the front of the truck followed by a sharp jolt made me wake up in a big hurry, within a second I was off the bunk and had whipped the curtains back expecting to see another vehicle in contact with mine, but nothing.
I got out and wandered round the truck, everything was shipshape and in orderly fashion. I even got the torch out and checked all the suspension airbags, but all were tight and inflated. Mystified I returned to the cab, and sat on the bunk wondering if I had been dreaming, when suddenly I felt that the truck was moving. Puzzled I looked at the handbrake and quicly sussed it was in the released position, and snatched it back on, the cab lurched forward as the brakes grabbed and the truck stopped.
The loud bang must have been the lever releasing itself, and the jolt was from the tension releasing in the drive axle brakes, as I had lowered the suspension to level the cab up as I was parked on a gradient.
The h/brake was definately applied on arrival, as I exited through the drivers door, and opening the drivers door with no handbrake applied sets off the bong bong alarm.
Since then I’ve tried several times to try recreate what happened and make it do it again by positioning the lever right on the edge of its point of locking, but it always either locks on fully, or immidiately releases.
Unlike most levers that have a sliding collar that drops into a hole, this lever seems to work a bit like a push button biro with some sort of rachet mechanism. I know one thing its scared the ■■■■ out of me, and in moments of no confidence and uncertainty I put the trailer brake on as well when parking 
The truck is an Actros MP2, anyone else had this happen 
,
This happened to me on a scania, pulled trailer brake by mistake. Have an Actros now and will watch out for this. Thanks for the post. Bet you walk back to your truck a few times to check it is on. I know I do, cant help it…
I believe MAN have had some issues over this and wonder if it’s the same handbrake.
Had a similar fault with a replacement handbrake valve (genuine scania) just recently in my 4 series.
The valve was replaced due to an air leak and had never released itself before.
On the first day after the repair the lever released itself twice, I thought it was just me being a ■■■■■■■■ 
but when it done it again the next day I immediately defected the truck and had the new valve replaced.
Never had another problem after the second new valve was fitted.
Do you believe in ghosts!!!..could be the truck is haunted 
Weirder things have happened before 
If you search back a few years, a good few years, I posted the contents of a letter which appeared in Transport Engineer concerning a Knorr Bremse parking brake which had self-released. Search on my username and Knorr Bremse/Transport Engineer.
Admittedly, it concerned a vehicle used for servicing the ‘construction’ Industry where the opportunties for the ingress of grit and garbage are more likely, but could apply elsewhere.
Maybe Volvo got the right idea with the broms brake?
was up the George Eliot Hospital Nuneaton on Friday night
(to do my radio show on @nker 1386am)
there was a small Hyundai abandoned half way across the car park
no handbrake applied i pushed it into its ■■■■■■■■■■■■ and wedged it with a breeze block 
Krankee:
If you search back a few years, a good few years, I posted the contents of a letter which appeared in Transport Engineer concerning a Knorr Bremse parking brake which had self-released. Search on my username and Knorr Bremse/Transport Engineer.Admittedly, it concerned a vehicle used for servicing the ‘construction’ Industry where the opportunties for the ingress of grit and garbage are more likely, but could apply elsewhere.
Funny thing that K, with visiting muddy farmyards and sites, dust is a big problem inside the cab when the mud dries out and blows around the cab when the door is opened, and was the only conclusion I could come to as to why it seemed to engage OK on that occassion.
I’ve done a search as you suggested but come up blank, I would be very interested in reading it.
I’d like to know more about Harry’s MAN revelation, what was the conclusion of the cause for the MAN/ERF to roll backwards out of the ferry doors recently, powder tanking is a dusty job too, maybe a link.
Lets say you were on a loading bay when this happened.
But you’ve handed your keys in, and are sat in a waiting room.
The truck roles forwards killing a bloke in the yard and the bloke doing the loading.
Who would be responsible.
limeyphil:
Lets say you were on a loading bay when this happened.
But you’ve handed your keys in, and are sat in a waiting room.
The truck roles forwards killing a bloke in the yard and the bloke doing the loading.
Who would be responsible.
They would, handing in keys never makes a truck safe and also the driver isn’t there to make sure it doesn’t go anywhere. They claim they are trying make unloading safe, when i fact they are doing noting about it. The trailer should be made secure to the bay somehow.
DAFMAD:
limeyphil:
Lets say you were on a loading bay when this happened.
But you’ve handed your keys in, and are sat in a waiting room.
The truck roles forwards killing a bloke in the yard and the bloke doing the loading.
Who would be responsible.They would, handing in keys never makes a truck safe and also the driver isn’t there to make sure it doesn’t go anywhere. They claim they are trying make unloading safe, when i fact they are doing noting about it. The trailer should be made secure to the bay somehow.
That could be a tricky one, ultimately the finger of suspicion would point at the the driver for not applying the brake in the first place. How many firms would back their driver and go out and spend big £’s proving that he had applied the brake, but that the brake had released itself
Its really put the wind up me, had I not have been in the cab when it flew off, I would of blaimed myself for being a dozy ■■■■ for not putting it on in the first place
Thanks for trhe post. I will leave it in gear in future.I had this problem with my car once.
alamcculloch:
Thanks for trhe post. I will leave it in gear in future.I had this problem with my car once.
I understand that you must never leave a diesel in gear, cos if the hanbrake is off (for whatever reason) the amount of energy to get it to bump start is small (say a forklift braking in the trailer or even a gentle slope) and it’ll start dieselling till it’s exhausted the residual fuel.
But on the other hand this could be something MMTM
MADBAZ:
alamcculloch:
Thanks for trhe post. I will leave it in gear in future.I had this problem with my car once.I understand that you must never leave a diesel in gear, cos if the hanbrake is off (for whatever reason) the amount of energy to get it to bump start is small (say a forklift braking in the trailer or even a gentle slope) and it’ll start dieselling till it’s exhausted the residual fuel.
But on the other hand this could be something MMTM
Nah, ignition would need to be on and engine nice and warm. Diesels have a “stop solenoid” which shuts the fuel off when the ignition is off and lets it through when the ignition is on. I suppose if you really had problems you could dump all the air when you parked but then you’d have quite a wait in the morning with the annoying buzzer or alarm for low air pressure 
MADBAZ:
alamcculloch:
Thanks for trhe post. I will leave it in gear in future.I had this problem with my car once.I understand that you must never leave a diesel in gear, cos if the hanbrake is off (for whatever reason) the amount of energy to get it to bump start is small (say a forklift braking in the trailer or even a gentle slope) and it’ll start dieselling till it’s exhausted the residual fuel.
But on the other hand this could be something MMTM
As said, you would need to be in the older stuff like a 3 series or something else with a pull fuel stop, if you turn off by the key, it can’t happen.
If you are worried that the vehicle may
move ,PUT two WHEEL CHOCKS on a WHEEL
front and rear, this will stop the vehicle moveing,
We had to do this ever time we pulled into
Du Pont IN CONTERN;lUX;
I can’t find the original thread either.
Perhaps it was on the Mk 1 forum and I’ve no idea where Rikki has archived that.
The discussion arose because someone had parked on a bay at Tesco, Middlewich, and then jumped on the bunk. The next thing they knew was that the vehicle had rolled across the yard into a waiting vehicle.
Having read the post, I knew that I had seen the letter. With a thunderstorm approaching, I had turned off my computer and began to leaf through some old magazine issues and found the letter. In those days I would have been on ‘dial up’ so it must have been a good few years ago. Also, it was before Tesco adopted the policy of not allowing drivers to remain in cabs.
Essentially, the easiest way to avoid it happening (with a trailer), is to apply the trailer brake. It only takes a few seconds, before and after, and can prevent a load of hassle should the unexpected result.
I hadn’t realised that such occurrences were so prevalent. Perhaps I will be applying the trailer brake more often having read this.
Harry Monk:
I believe MAN have had some issues over this and wonder if it’s the same handbrake.
Quite possibly. Ancilliary items, such are parking brake assemblies, can often be sourced from a single supplier across a range of ‘badges’. Often it will be just the ‘plastic’ bits that change and, even then, some of the plastic bits (on the retention/actuation side) may well be sourced from a common supplier.
Krankee:
I can’t find the original thread either.Perhaps it was on the Mk 1 forum and I’ve no idea where Rikki has archived that.
The discussion arose because someone had parked on a bay at Tesco, Middlewich, and then jumped on the bunk. The next thing they knew was that the vehicle had rolled across the yard into a waiting vehicle.
I can remember the post being discussed, a DAF CF if I remember and the guy was in danger of losing his job, it had happened to others to.
Going to call in the Merc dealer this morning, see if an MP1 hand brake valve will fit, its the old fashioned sliding collar type.