Hydraulic cylinder question on Case loader

[HankOH]

I just acquired a 1965 Case 530 with an original Case loader (model 190 I believe). There is an attachment on the bucket cylinder that I need help identifying - it looks like the size of a hydraulic motor - the hoses from the tractor go to this attachment, then hoses lead from the attachment to the cylinder. What is this? Is it original? (I have a manual from an earlier 190 loader that does not have it).

Thanks for any help.

 

[1031D]

The book calls it a "hydraulic interlock" must be like the old MM cylinders that have a valve in them to prevent the ram from settling under load.