Hurth Hydraulic Transmission

  The following Trouble location chart is intended as a basic guideline for the trans itself. Considerations such as engine and hull condition, as well as prop and shaft condition need to be evaluated first. Always try to shift the unit at the trans (disconnect the shift cable) to evaluate hard shifting, as it is usually caused by the cable to the trans and not the trans itself...
1. Transmission gears  cannot be shifted
      A. Shifting lever loose. Tighten clamping screw on shifting lever
      B. Remote control does not permit lever travel required for testing
         Lift remote control off, if gears can be shifted by hand,
         correct remote control
      C. Remote control faulty.   Repair remote control
      D. No shifting pressure available.  Refer to 7
2. Gears are shifted sluggishly
         Lever travel of remote control is too short;
         lever shift just short of minimum traveling distance.
         Lift remote control off, if gears can  be shifted by hand,
         correct remote  control

3. Clutch is slipping; propeller speed too low as compared to engine speed
       A. Incorrect fluid used
             Drain and refill with correct  fluid,
             flush transmission while  engine runs
             in neutral position,  drain fluid, refill
             transmission.
       B. Fluid contains water Refer to 9
       C. Shifting pressure too low Refer to 6
       D. Wear on clutch discs
             Disassemble transmission replace clutch discs
       E. Piston rings in clutch are  damaged
             Disassemble transmission, replace clutch   
4. Transmission is blocked
       A. Medium piston ring in input shaft in control block is faulty
             Remove control block, replace  piston ring,
              replace control block if worn.
5. Output shaft turns in neutral position
       A. Rotary slide valve in control block is worn
             Replace control block
       B. Faulty needle bearing on input shaft
              Disassemble transmission and
              input shaft, replace bearing
       C. Dished discs due to overheating of slipping clutch
              Refer to 3

6. Shifting pressure too low
       A. Fluid filter dirty
              Replace fluid filter
       B. Fluid level in transmission is too low
              Fill with fluid; check for fluid loss
              in transmission, cooler and pipelines
              lines for leaks also refer to steps 10 to 13
       C. Fluid pump is worn out
              Replace control block together with fluid pump
       D. Piston rings in input shaft in  control block are faulty
              Remove control block and  replace piston
               rings. also  replace control block
       E. Piston rings in clutch are faulty
               Disassemble transmission, replace clutch

7. No shifting pressure
        A. Direction of engine rotation does not agree
           with arrow on  transmission
                Replace with L.H. rotation engine
        B. No fluid in transmission
                Refill with fluid
        C. Fluid filter is dirty
                Replace fluid filter
        D. Fluid level in transmission is too low
                Fill with fluid; check for fluid
                loss in transmission, cooler and
                pipelines lines for leaks also
                refer to steps 10 to 13
       E. Fluid pump is worn out
                Replace control block together with fluid pump
       F. Fitting key in input shaft for fluid pump drive is broken
                Remove control block. Replace fitting key
                and any other faulty parts
       G. Shifting pressure relief valve  spring is broken
                Replace control block

8. Excessive fluid  temperature
       A. Excessive fluid in transmission
                Remove excessive fluid with commercial fluid pump
       B. Fluid cooler is dirty on water side
                Remove coolant lines and  clean fluid
                cooler on water side.
       C. Worn fluid pump in control block
                Replace control block and fluid pump
       D. Faulty piston rings in input shaft in control block
                Remove control block, replace piston rings
                in input shaft. Check control block and
                replace if damaged from faulty piston rings.
       E. Clutch is slipping     Refer to 3
       F. Clutch does not open  completely due to worn clutch discs
                Dismount transmission, replace inner disc and
                all faulty parts.
       G. Clutch does not open completely due to broken clutch cup
           springs. Disassemble transmission,  replace inner disc
           support  and/or clutch
       H. Low water flow from sea pump
                repair or replace sea pump

9. Water in fluid, fluid looks  milky
       A. Fluid cooler faulty
                Repair leakage at cooler or 
                replace cooler.
       B. high water level in engine compartment, water
           entering at output shaft seal
                Remedy cause for water level in engine compartment,
                change transmission fluid

10. Fluid leakage at input shaft
       A. Breather clogged by paint or  dirt
                  Remove dirt or paint from breather.
       B. Shaft seal faulty
                  Disassemble transmission, replace seal.
                  If seal location on input shaft is
                  worn repair surface

11. Fluid leakage at output shaft
        A. Breather clogged by paint or dirt
                  Remove dirt or paint from breather
        B. Shaft seal faulty
                  Disassemble transmission, replace seal.
                  If seal location on input shaft is worn
                   repair shaft surface

12. Fluid leakage at venting filter
       A. Excessive fluid in transmission
                  Pump out excessive fluid with commercial hand pump

13. Fluid leakage at joints or screw connections
       A. Bolts are not tight
                 Tighten bolts to specified torque
       B. Seals on bolts have been reused several times
                 Replace seals, tighten bolts to specified torque

14. Fluid leakage at filter cap or breather
      A. Filter cap not flush or tight
                 Reinstall filter cap flush with
                 housing and tighten
      B. Filter cap o-ring damaged

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