Tell me about 12v solenoids.

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  • Tell me about 12v solenoids.
  • Premier Icon Stoner

    nice idea, bit moon on stick though shirley?

    I think I have a range rover 200Tdi handbrake on my lump and it’s fantastic. Will lock transmission with barely a finger of effort.

    And thinking of braking force, without the vacuum on the brake (when engine off) it probably needs fair heft on the pedal – obviously while sitting ticking over when you open the gate it would have the vacuum working.

    What about fitting an Xbrake (disc handbrake)? I wonder if it can be fitted together with the normal handbrake?

    Premier Icon Stoner

    …and I reckon the force required to engage the disc hand brake would be low enough to use some kind of electronic actuation – even a servo.

    Now you mention it, I think servo may have been the word I was looking for, not solenoid.

    I know some modern cars have electronic hand brakes, although I know nothing about them other than seeing special tools for adjusting them in tool catalogues.
    I’ve also seen disc transmission brake conversions on Land Rovers.

    This could be the way to do it.
    Make an adapter to bolt a disc in place of my hand brake drum, then make an a bracket to hold a caliper.

    I need to learn about electronic parking brakes now. How they work, how much they cost, how to set them up and so on.


    TBH would it not be easier to just carry a large item you place under a wheel or in gear and engine off. Any solution will be both complex and expensive.

    Yes, a wheel chock would do the job, although there’s always those few seconds between stopping and placing the chock under the wheel when there’s no runaway protection.
    It’s the anti-theft bit I’m after as well though.

    The E-Stopp looks like what I want, I could connect it to teh standard land Rover cable operated transmission brake.
    $450 with no European distributor. I’ll keep looking for a cheaper way.

    From the little bit of research I’ve done on electronic parking brakes so far, it looks like they are controlled by the vehicle’s ECU, so not an easy conversion.


    We use something similar to this on one of our race cars as a starting aid for one of our drivers who is disabled

    I’ve got an idea for a bit of an unusual job for a solenoid.

    Some trials Land Rovers use fiddle brakes, a bit like the independent brakes on a tractor.
    The usual method is to two brake master cylinders in the pipes to the rear brakes, operated by manual levers in easy reach of the driver, a bit like two extra hand brake levers.

    There is an anti-theft device available, which is simply an electronically operated one way hydraulic tap in the clutch pipe. Once the clutch pedal has been pressed, it stops the fluid returning, so the clutch stays disengaged and the vehicle can’t be driven.
    It costs about £400 last time I looked though, which sounds a bit much for a tap to me.

    I want to combine the two.
    I live on a steep hill and sometimes need to stop to open my gate with a trailer on. I always worry about the handbrake holding, so it would be good if I could lock the rear hydraulic brakes on too.
    If I could do it electrically with a hidden switch, instead of using an obvious lever, it would be a good anti-theft device as well, preventing the Land Rover being driven, or even towed, away.

    So, what I want is a solenoid that will push a brake master cylinder hard enough to lock the wheels. I don’t know how much force that would take, 50kg maybe ? A longer lever would reduce the effort, but then it would need a longer stroke.
    It must also lock in position with no current drain for when it’s parked. So it needs some sort of ratchet that disengages when switched to release.

    Moon on a stick, or is there something made for radio control models or automated machinery that’s just what I’m looking for ?


    Stoner- your rear gearbox seal just hasnt let go yet. It will happen – trust me an your hand brake will be useless.

    I find switching the engine off an leavin it in gear works quite well when im parked

    Btw good luck getin through an mot with fiddle brakes fitted we have had hassle at the local club with that

    Thanks Neil, that looks like it would do the job.
    A bit of searching and it looks like the similar MechLock, which is what I half remembered seeing before, is no longer available, although there’s mention of it, and it’s £390 price, on Land Rover forums archives.

    Another similar item from the UK.

    These don’t actually apply the brake, all they do is hold the pressure in the pipe.
    With my old drum brakes on the rear, that should work OK. As the drums cool down after driving, they will contract and jam the brakes on harder.
    I don’t know if they would work on discs, as the opposite would happen and the brakes may release after a while.


    I got ours from Competition Supplies @ Silverstone.

    Looking in to this and thinking about it a bit more, these line locks only hold the pressure in the line, are only rated for short term use and draw almost an amp.
    They would be good as an anti-rollaway device while opening a gate, but not for anti-theft.
    I would need to press the brake pedal, then switch it on. If I came back to the Land Rover a few days later I’d probably find the solenoid had burnt out or the battery was flat.
    I could get round it by wiring it up to a pressure brake switch, as used on Series Two Land Rovers, so it only activates when the pedal is pressed, but it’s starting to get a bit complicated now.

    Premier Icon richmars

    To get around the current use, you need a solenoid that is powered to release the brake, so the brake is only released when the engine is running. You can add a switch to lock it when the engine is running.

    Still sound a bit iffy to me.


    Hows about a windscreen wiper motor, with an excentric “cam” on the end to push the pedal down. WW motors use worm drive gearboxes and so are effectively locked when not powered, which would keep the pedal from springing back. Use a small rear window wiper motor for better packability. You also probably don’t need to arrange the motor to reverse, just make the cam the right height so it can continue round in the same direction to release.

    Having said that, leaving the service brakes jammed on isn’t really recommended tbh.


    To get around the current use, you need a solenoid that is powered to release the brake, so the brake is only released when the engine is running. You can add a switch to lock it when the engine is running.

    Still sound a bit iffy to me.

    Yes it is. Any failure of the solenoid or the power feed to the solenoid would close the line lock making the brakes unusable, ie it doesn’t fail to safe.

    On reading the OP I was going to suggest that the nearest thing was an electric line lock (as already suggested), but really only useful as a short term parking brake.

    Even a mechanically applied line lock isn’t great as a long term parking brake. Which is why one reason they are not allowed as parking brakes on road going cars (another is they can’t be applied independently as an emergency brake). The DVLA even revoked the exemption that allowed fully EU type approved quads with hydraullic parking brakes to be UK road legal, because after being parked on an incline for 2 weeks there was potential for it to roll away.

    What you are asking for is fairly simple if you just want to go down the mechanical route, hydraulic handbrakes are fairly standard mod in rally cars and are used alongside std parking brakes.

    You plumb it into the brake lines to the rear – where you may fall foul is that rally cars tend to be plumbed Front & Rear NOT diagonally opposite as a road car – i.e. Front Left & Rear Right on same circuit (could be covered under construction and use). Rally cars tend to have two master cylinders up front too one for the front one for the rear – basically allowing you adjust the bias F – R depending on surface / conditions.

    Anyhoo I over complicate.

    Basically you install an extra master cylinder in the vehicle that is operated by an handbrake lever just for the rear brakes, now normally in a rally car this won’t have a ratchet on it – ergo it files off when you pull it, thus rather usefull for turning the car in tight corners, but if you are looking for a parking boost then install/ retain the ratchet.

    Like this 😛

    But as has been said above I would retain the std landy transmission brake.


    The rally style hydraullic handbrake is basically a fiddle brake that operates on both rear wheels at the same time rather than individual, and allows the rear brakes to be applied independently of the fronts when the car is moving. For a parking brake scenario that MTG is asking about a line lock would be a simpler solution, as there is already a master cylinder that applies the brake pressue, just need something to hold it. This is a method that is also used in some rally/race cars.

    Alternatively for a simple solution (to the parking brake issues) as suggested above speak to Si and get an X-Eng disc brake, or fab something up yourself as everyone used to do before the days of X-Eng.

    length of rod cut to fit between the seat base and the brake pedal?

    If you want to get facy you could have it slide out from under the seat to jam the footbrake on and then padlock it in place.


    if you really want a line lock how about just routing it via a needle valve?

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