Winfield DSF/HBS Anchor Head Rebuild Instructions


  1. Remove the chain (or cable) head catch mounts from the anchor head.
  2. Remove aluminum anchor head assembly from the base unit.
  3. Disassemble the head completely. To remove the 1 1/4 master piston, use expanding snap ring pliers.
  4. Remove all odd o-rings and wash all components in mineral spirits.
  5. Inspect the pistons for raised burrs and polish, if necessary, using #400 grit production paper.
  6. With clean hands, install new o-rings in all grooves. Pre-lube the groove with “Hydraulic Jack Oil”.
  7. Pre-lube the valve body and piston bores.
  8. Install the valves into the valve body turning them as the o-ring enters the bore.
  9. Install the piston into the anchor head from the number plate side.
  10. Install a piston plug in each of the bores. Push in slowly to allow the o-ring to seat. IMPORTANT!! Be sure that there is oil around the lip of the bore.
  11. Bolt the number plate to the head. The #1 should be away from the operator.
  12. Placing the head upside down, install the spring plungers and retaining bar (or caps on older units).
  13. While upside down, move the head to the edge of the bench so that the valve body mounting holes are accessible from the underside.
  14. Place the valve body on the head insuring that the feed hole in the valve body mounting holes are accessible from the underside.
  15. Push all 5 valves into the head (closed) and replace the 4 bolts. Make contact with all 4 bolts. Then lightly snug them starting with on of the middle bolts. As you would with a cylinder head, alternate bolts until all are tight.
  16. Reinstall the knobs on the valves and install the button head screws with the o-rings in the ends of the valve body. Do not over-tighten these screws – over-tightening may cause permanent damage.
  17. Stand the head on end with master bore facing up, and fill the master bore with “Hydraulic Jack Oil”.
  18. Open the valve closest to the master bore and, using a pair of needle nose pliers, slowly pull out that piston. The oil in the master bore will go down. Push the piston back in. The oil will rise and air will be expelled. Continue this until there is no air remaining. Close that valve.
  19. Repeat this process with the other 4 valves and pistons. When all the air is out, refill the master bore to the top.
  20. Place the master piston in the bore (oil will be displaced and overflow). Continue to slowly push the master piston into the bore. One or more of the 5 pistons will start to move out. Stop when the top of the piston is even with the head.
  21. Install the feed knob assembly with the knob fully retracted.
  22. Place the head upside down on the work bench with the 5 pistons facing you. Put a block of wood or other suitable stop behind the head preventing it from moving back.
  23. Loosen the button head screws at either end of the valve body. Using a second block of wood, apply pressure to the 5 pistons. Oil will start to leak from the screws along with any leftover air. When the 5 pistons are retracted, retighten the valve body screws.
  24. Replace the datum plate o-rings and datum plate. Note! The o-rings used with the datum plate do not seal oil. They can be washed and reused. If new o-rings are needed or desired, a kit is available.
  25. The anchor head is now ready to be reinstalled on the base unit.
  26. Trimming the datum plates after reinstallation is recommended.
  27. All the o-rings used are standard size Buna Rubber.
    1. 3/8″ o.d. x 1/4″ i.d.              #010 Valve stems and button head screws
    2. 5/8/” o.d. x 1/2″ i.d.            #014 Anchor pins, pin plugs and valve body
    3. 1″ o.d. x 1 1/4″ i.d.              #214 Master Piston
    4. 7/16″ o.d. x 5/8″ i.d.           #First datum plate seal in anchor head
    5. 5/8″ o.d. x 13/16″ i.d.         #114 Second seal in datum plate
  28. Anchor heads made before 1997 had 2 o-rings on the valve stem, and since 1997 there have been 3.