Hi, Just a small question here regarding engines being governed to the units max speed. The reason I am asking is that when taking the 166 out on the GWR It was very easy in taking the unit up to a speed of 100mph plus even when it states in the cab MAX SPEED 90mph. I would have thought this would be mandatory.
It was certainly common for some older UK traction units to be fitted with overspeed trips, though those would only kick in if the train was under power at the time. That said, most trains tended to have a bit in reserve. I have heard tales of Class 159's on the Waterloo to Exeter route getting up to 100 MPH (even though the line speed is only 85!) and HST's were well known as being easily able to exceed their service maximum of 125 MPH. The deterrent these days is that all trains are fitted with OTMR or similar (black box) which can be monitored and checked to see if and when maximum speeds were exceeded. Mind, I'm surprised you were able to wind the 166 up that high - the brief bit of a run I did yesterday evening it still seemed quite sluggish, which is actually true to life. These units are not particularly quick off the mark.
I thought locomotives and trains were specified with a maximum permitted speed that ensures safe operation, not the speed actually achieved during testing. Last year, we had a disaster in our country when a train driver with over 20 years of experience was driving a diesel locomotive to remove a faulty train from a section of the line. He turned off all safety systems and accelerated the locomotive from the permitted speed of 160 km/h to a speed of over 200 km/h, according to the data from the black boxes. He maintained this speed for quite a long time, and the accident happened on a curve with a 60 km/h speed limit, which he entered at a speed of 140 km/h. I think that most locomotives and trains can significantly exceed their certified speed.
Extreme example, the BR182 / Taurus is allowed for max 230 km/h. This loco broke records while driving 357 km/h....
A lot of the old BR locos were not speed limited at all, they'd in theory allow you to drive right up until the speed the traction motor armatures burst at (usually around 150% the max speed). The 08s were particularly good at bursting armatures usually resulting in bent coupling rods or sheared crankpins as that would occur somewhere between 25 and 30mph which isn't much above the design max of 20mph due to the extreme gearing. The London Midland region (alone oddly) then reduced the maximum speed on paper down to 15mph to build in a greater speed buffer in an attempt to discourage overspeeding. Diesel Mechanical and Diesel Hydraulic locos do however sort of self limit themselves. Once the transmission input speed, and the engine speed match they will cease to accelerate, when the diesel engine reaches its max design RPM the governor will cut fuel back to prevent an overspeed and this will become the limit. A first gen DMU for example once 2000RPM ish has been reached in 4th gear thats as fast as it will go under power, although thanks to the freewheel you can technically go faster downhill under gravity but the engine won't be providing drive. A Class 03/04 type loco doesn't have a freewheel though so once they reach the max speed in 5th any acceleration past that will cause the diesel engine to engine brake somewhat preventing overspeeding (although it will cause the diesel engine to overspeed if the gradient is severe enough). Think Diesel mechanicals/hydraulics with the exception of shunters usually require about a 10% overspeed to be possible just to build in a bit of a buffer to allow the design max to be reached and not at the point where the engine is being red lined.
It certainly used to be the case in the UK that as part of certification you had to demonstrate a 10% over speed (so 99 mph in a 90 mph unit etc)
Both of you are incorrect. Class 66 normal gearing are limited to 81mph. 77mph will be a power removal, and if you hit 81mph the brakes will apply. Class 66 low gearing are limited to 75mph. 67mph will be a power reduction and if you hit 75mph brakes will apply.
Apart from an increase in the overhead voltage and the dismantling of a few obstructive small parts on the locomotive, no special adjustments were made. It was a light loco run, the loco is now OBB owned and still drives around.
I know in game the 47 isn't limited I did the LE move from Lancaster to Preston and just went full throttle expecting it to max at around 90mph. Was looking at the scenery then checked the map and I was doing 127mph. IRL could the 08s be towed at more than 15mph. I have seen pics on FB groups of them doing moves over the hope valley under their own power and thought I bet that was a boring (and inconvenient job) to do.
You can tow a Class 08 at faster than 15mph but you have to take something off the locomotive to allow for it, and it's not a great job to have to refit it once removed.
In many cases the Vmax isn't determined by the motive power but by the trucks and suspension. This was the case for example with the BR E 10s/110s, which in their original form were limited to 140 except for the relative handful refitted with high-speed bogies (these would be tagged E 10.12 > 112, and 114)* No change to the motors, transformers or gearing, just wheels rated for higher speed. *Not to be confused with the later 143-family 112 and 114 we have in the game
Jokes aside, this indicates that there is clearly a problem with the physics (running resistance or something like that)...
To tow an 08 quickly (over 10mph I believe) two things need to be done, the coupling rods need to be taken off which is not a 5 minute job and they're chuffing heavy, and then on each of the two traction motors there are screw threads which need to to be wound down which effectively jacks the traction motors up demeshing them from the reduction gearboxes... this generally involves whichever poor sod going in with nice clean overalls and coming out pitch black as the underside of 08s are covered in thick oil and grease. Then when it gets to the destination the process needs reversing... which is made even more fun by the fact the wheels will no longer align, so you need to jack the locomotive up and probably grease the rails, spin two axles to they align, put the first rod section on, drop it down, jack the other end up, rotate that remaining axle and put the last section of rod on. Basically a complete pain in the backside! Also 127mph sounds perfectly reasonable for a Class 47 light engine at full power, its max speed design speed is 95mph, there are no electronic nannies so there is nothing physically limiting it to 95mph and light engine there is practically no load on it. The traction motors will have a design max speed of about 142.5mph before they will fail from the armature bursting (1.5x rated speed). Heck there are even documented evidence of them doing over 100mph with a loaded train! The only thing is the brakes are defintiley not up for 127mph running, light engine its max 60 or 75mph only for a reason!
Having seen a bent coupling rod on an 08 dealt with - it's not a fun job. (very glad to not have to be involved in that one)
