Hello, my new steed is an old ERF ECT with the ■■■■■■■ M11 engine. It has a two stage engine brake which is very effective. Could anyone tell me for my own curiousity what kind of engine brake it is, I assume an exhaust brake although I know the ECX ERFs had Jacobs brakes? Ta in advance.
If it’s an exhaust brake it will make a noise when in operation. That’s the easy way of working out what it is. Also, the exhaust brake will only operate with fairly high revs whereas the Jakebrake wont be noisy and will operate at lower revs. You would normally get more than 2 settings with Jakebrake.
Hope this helps, Pete 
You must have had a good un Pete.
We had a ‘H’ reg…what year is that? H63 OOM was the reg number,an ex petrol regs unit with double drive,an overkill for fuel work!..fitted with 14 litre ■■■■■■■ with a two stage jacob or ‘jake’ and that was noisy enough in service,certainly louder than an exhauster which when you consider it turns the engine into a compressor is no surprise really.
Thanks for the replies. I am slightly confused as I used to drive decommissioned RAF units (private land) which had jakes and they were very noisy. 
I will dig the lorry’s manual out see if there is anything in there.
I’ll halt the confusion now!! I wrote that post at the end of an extremely long day and I got it wrong. Jake brakes can be noisy. I simply got confused with retarders which are not.
Apologies for the error - - only human!!
Pete
No problem Peter!
I read the effin manual and found my answer.
ERF jake brake by KevinMillsEsq, on Flickr
What’s a bremsomat?
It’s a type of free-wheeling device. Don’t know any more than that. (Thanks to Google!)
Pete
Ta Pete…see,none of us are too old to learn…to listen maybe but not learn.