“Jake” engine compression brake is a hydraulic teeter-totter. It uses the valve actuation of one cylinder as a hydraulic pump to burp another cylinder’s exhaust valves open momentarily at the top of its compression stroke. This prevents that cylinder from acting like an air spring. It essentially turns the engine into a big air compressor of 100% waste, momentarily. This is why they work in pairs, and is a bridge mechanism over sets of rocker arms. The solenoid on them simply opens or closes the flow connecting 2 cylinders rocker arm pistons. Important this is done on decel (fuel cut) only, otherwise it will cause misfire.
Jake brake actuators are made by Jacob’s manufacturing. They are not available for an LDT/S engine. They should be available for the Cummins 855. They can be setup to activate in stages. I installed these on an ISL engine, and studied it to a medium level before putting something on that I did not understand.
Separately, an engine exhaust brake can be decently effective as well. Cummins lists their exhaust brake for an ISCL (8.9L) as being able to absorb up to
164hp of braking energy at the governed 2200rpm. The compression braking (ie Jake brake) absorption ability is somewhat higher coming in at about 200hp of absorption @ 2200r's. Need to check and possibly uprate exhaust valve springs when doing exhaust brake though. This is an interesting chart:
https://quickserve.cummins.com/info/qsol/products/newparts/jacobs_md_nondodge.html An ISC (8.3L) is able to exhaust brake about 151hp of absorption energy @ 2200r's. For Cummins medium duty engine sizes, compression brake actuators were not available until they went to 4 valve "I" series electronic engines. Jake brakes for heavy duty (big bore) engines have been available for a long time, even back to 2 stroke Detroit Diesels.
I don't know any of this data for an 855 engine, but if you look it up for a modern ISX, it should get you in the ballpark. The above was just useful to illustrate the difference in exhaust vs compression braking ability, and a 2 second tutorial of how it works. Simp and a few others here are successfully using Jake engine compression brakes on their 855 based engines.
what I found on the Internet about my crane is that it's rated for 18000 KG. I don't know how many ton that is?? I added a few more pics one is of the on/off switch and 3 way switch in the cab marked Jacobs engine brake the other is of my nose bump and last is a different angle of the pods they say Jacobs on them but I cant find a part number or any other info on them I will look again this weekend.
