referring to fig1 - 7 , there is shown one embodiment of this invention wherein a hydraulic valve spring compressor tool 1 , consists of a c - shaped frame 2 , formed from round tubing which has a spring seat bracket collar 3 , at one end , welded thereto and a slave cylinder assembly collar 4 , welded to the other end . collars 3 and 4 , as shown in fig2 allow adjustment by means of a gap 8 , in the collar and an adjustment tube 6 , welded on one side of the gap , and the adjustment boss 5 , welded to the other side , the boss is threaded . when a bolt 7 , is placed thru the adjustment tube 6 , and threaded into the adjustment boss 5 , then the bolt 7 , is tightened , this closes the gap 8 , and creates a clamping effect on the device it holds . the spring seat bracket 11 , shown in fig5 which consists of a tube section 12 , welded offset to a flat disc 13 , that is strengthened by gussets 15 , the flat disc 13 , has an access hole 16 , for valve stem and valve locks to pass thru and is centered in place by retaining lips 14 , which incompass the outside edge of the disc 13 , on the side which contacts a valve spring seat , sometimes referred to as a retainer . the slave cylinder 4 , holds the slave cylinder assembly 20 , shown in fig4 which consists of a cylinder housing 21 , with a cap 22 , which is threaded in place . the slave cylinder piston 24 , seals to the housing 21 , by means of a cupped piston seal 25 , which lies in a machined groove 33 , in the piston . the other end of the piston 24 , is also sealed and centered by means of an o - ring 23 , in the housing cap 22 , the piston 24 , has a threaded hole 28 , which the valve contact head 29 , and the front spring plate 27 , mounts onto . a return spring 31 , extends form the front spring plate 27 , to the rear spring plate 26 , there is a return spring 31 , on each side of the slave cylinder . the rear spring plate 26 , also has a hose connection port 30 , which the hydraulic hose assembly 32 , threads into allowing fluid transfer to and from the master cylinder assembly 54 . in fig5 we see the master cylinder assembly 54 , in place in the master cylinder pedal assembly 40 , which consists of a rectangular shaped platform 41 , made of angle steel welded together . the pedal 44 , is made of square tube steel and is formed in a rectangular shape with one end having a round tube referred to as the pedal mounting tube 45 , which the pedal pivots on and mounts to the pedal hinge plates 43 , with a hinge plate on each side of the pedal mounting tube 45 , and connecting thereto by means of a bolt 50 , passing thru both hinge plates 43 , and mounting tube 45 , with a nut 51 , screwed onto the bolt to secure it in place which is clearly shown in fig6 . at the center point of the mounting tube 45 , on the bottom side there are two leverage brackets 46 , and are welded in place . these brackets have an attachment hole 48 , in which they allow a bolt and nut 52 , to be used to connect to the master cylinder linkage 59 . a master cylinder mounting plate 42 , is welded upright with a hole in the center , large enough to allow the master cylinder assembly 54 , to pass thru so the master cylinder bracket 62 , can contact and bolt to the master cylinder mounting plate 42 . a bolt passes thru the mounting bracket holes 63 , and screw into the threaded holes 49 , in the master cylinder mounting plate 42 , on the pedal assembly 40 . in fig7 we can see the master cylinder assembly 54 , consisting of a housing cylinder 55 , which is threaded at one end which allows the housing cap 60 , to be placed thereon , near the center of the housing we see the mounting bracket 62 , and at the closed end of the housing there is a hose connection port 64 , which the hose assembly 32 , threads into and allows fluid transfer to the slave cylinder assembly 20 , inside the housing there is the master cylinder piston 56 , which has a cupped seal 57 , placed in a machined groove 65 . the cupped seal 57 , makes contact with the inside of the housing 55 , to seal off the hydraulic fluid and to center that end of the piston 56 , at the other end of the piston we see a threaded hole which is the linkage mounting hole 58 , the linkage 59 , which connects the pedal leverage brackets 46 , to the master cylinder piston 56 . in the master cylinder cap 60 , there is an o - ring 61 , which lies in a machined groove 66 , this o - ring helps to seal the cylinder and center one end of the piston 56 .