torque Converter

• functions:
  • torque multiplication
  • fluid coupling
• depend on
  • velocity - speed
  • viscosity of fluid
  • volume - large impeller/turbine
• input: impeller (pump) connected to.engine
• trans: turbine connected to trans
• pros (fluid coupler)
  • no mechanic conn: cannot shock load, engine or drive train
• cons
  • high slippage in high rpm
  • heat
  • fluid coupler can not increase torque.
• vortex: t slower than i, applied brake, loss of heat, no or low speed
• rotary flow, same speed
• phases - (refer to functional phase) or relationship of the impeller and turbine relative to energy transfer
  • converter phase (vortex flow) impeller is faster than turbine
  • coupling phase (rotary flow) same speed
  • lock up improve efficiency, controlled by governor
• stage - turbine elements (# of times the oil strike turbine before returning to the impeller)
• warm up engine, trans by create loss of vortex flow, warm tc oil, thus trans oil warm up.
• stator purpose is to increase torque, redirect (circulate) oil flow back to impeller, reuse the energy oil the throwed oil. (3.5 times torque increase), multiply torque on starting up
• unlock lockup clutch on speeding up
• lock when i and t speed are similar
• haul truck run fixed stator ( stop and run all the time) want torque multiplied
• multiple stages will multiply torque more
• stall speed, full rpm on input (impeller), no output (turbine stop), should get the specs
• mul impeller, freewheel low load, lock more torque.
• 2 turbines
• torque converter oil
  • oil passage way around the shaft
  • oil input is inside the shaft
• the spring on lockup clutch helps dampen shock load from engine or torsion vibration from each power stroke
• lock impeller & turbine to provide mechanical connection between engine and trans, improving efficiency
• excessive temperature of torque converter can cause failure on trans, O-ring,..
• transmission uses very light oil (light viscosity, viscosity index very good => very little change with temperature).
• housing
  • dry (more common in heavy duty)
  • wet

torque divider

• use wet housing, need scavenging pump to remove the oil from housing
• combine torque converter and planetary
• more torque multiplication
• for the stop to get moving
  • pc is held
  • input sun, impeller
  • turbine (internal gear) spin the opposite compared to impeller => more speed difference => provide ton of torque when first starting
• stall test
  • engine w.o.t
  • apply brakes
  • typically in top gear (most load)
  • result cases
    • high stall speed (transmission problems)
      • too easy to turn
      • too low level, oil too thin
      • clutches slipping
        • try another gears, if speed change according to gear, slippage in trans
        • steering
    • low stall speed (tc problems)
      • low power engine
      • slipping in stator (should be lock , but it slips backwards)
    • heat (max 30 sec, excess 250F)
      • let it go down after test, put in neutral.
      • stator is seized when it suppose to freewheel
• service may need to pull trans out
• don’t move equipment to wash place, inspect it first! if it already washed run it a while to see leak
• make sure your bucket clean before drain trans, make it easy to determine problem
• submere tc, supply air, looking for air bubble