Month: October 2016

Current Measurements:
Current measurements are very helpful when troubleshooting electrical circuits. The current rating of components can be used to determine their condition. Current measurements allow you to determine the current draw as the component operates.

The engine starter, for example, will draw more than the rated current when overloaded, this higher than rated current flows usually indicates a problem which can cause additional problems. 

 


 

Inductive Current Clamps:

Most Digital Multi-Meters (DMM) or Digital Volt Ohm Meter (DVOM) only measure DC/AC current up to 10 A. For higher measurements an inductive clamp must be used, which measures current from .01 A to 1000 A, it does so by measuring the strength of the magnetic field around a conductor.  Some current clamps can measure AC currents only, which is not useful in vehicle applications. Ensure that the one you use or is capable of both AC and DC.

The clamps use Hall Effect sensor to measure the strength of the magnetic field produced in a ring of material that is temporarily placed around the current-carrying wire to measure DC. The greater the amount of current flowing in the wire, the stronger the magnetic field that is produced in the ring. To measure AC the clamp acts as part of a transformer to produce a measurable value.

 


 

Current clamps are a standalone accessories for your DMM or built into multi-meter:

Standalone clamps output a voltage value per measured amp. Most clamps have an output of 1 millivolt per amp. If the multimeter shows a measurement of 10 millivolts, the current flowing in the wire is 10 amps. If the voltage displayed on the multimeter is 100 millivolts, the current flowing in the wire is 100 amps.

In clamps that are built into a multimeter, measuring the current flow is as easy as selecting ‘current’ on the function selector, the value is then displayed in amps.

amp clamp, current probe, fluke
Fluke Amp Clamp (standalone)
Fluke Built-in Current Clamp
Fluke Built-in Current Clamp

 


 

 

Setting Up to Measure with Standalone Clamp (clamps that produce voltage): 

1. Turn the dial to mVac for ac current, or to mVdc for dc current on DMM.
2. Plug the black test lead into the COM jack.
3. Plug the red test lead into the V jack.
4. Zero the clamp by rotating the “zero” knob (some clamps do not require adjustment). Adjust until reading is on or close to 0mV.

 

current clamp, fluke clamp, current probe
Zeroing Clamp

5. Position the clamp over the conductor to be measured. With some clamps current flow orientation must be followed, point the arrow on the clamp towards direction of current flow. To prevent the clamp from picking up stray magnetic fields, separate the test conductor from surrounding conductors by a few inches. If separation is not possible, take several readings at different locations along the same conductor. Do not measure shielded conductors, as the magnetic fields are greatly diminished or even eliminated.

Note: Make sure circuit is energized to perform test.

Current Clamp Setup
Current Clamp Setup

6. View the reading in the display. On some DMM’s the mV scale only reads up to 600mV, if you expect to read a higher amp value change the setting to the Vdc scale and take your reading there. ensure to keep track of prefixes to the measured value.

current probe, amp measurement, amp draw, starter draw
1 to 1 conversion

Good Luck!

 

 

 

 

 

Description:

The Vapor door motor is an air-operated geared differential device with two horizontally opposed cylinders of different diameter size. A rack gear connects the pistons within the cylinders, the rack gear meshes with a rotary gear to convert straight line motion of the pistons into rotary motion. This rotary motion will rotate the teeter plate which moves the connecting rods to operate the doors.

Vapor, Doors, Assembly
Vapor Motor Door Assembly

 

 

 


 

 

Operation:

The Vapor differential motor operation:
1. To close the bus door, the large cylinder is charged with air thru an air solenoid, the large piston overcomes the air pressure in the small piston moving the rack gear to close the doors. The rate at which the door closes, depends on the closing speed adjustment and how air volume is allowed to the cylinder.

Vapor, door, differential
Door closing, large piston overcomes small piston to close door.

 

2. To open bus door, air to the large piston is shut off. The small piston being pressurized with air, will push towards the large piston. This will cause the air in the large piston to exhaust and cause the door to open. The rate of opening speed is controlled by the opening speed adjustment, by controlling the air exhaust rate.

Vapor, differential, motor
Door opening, air is exhausted from large piston side, this allows small piston to open door.

 

3. Cushioning effect, is used to control the doors from slamming when opening. As the large piston comes to end of it’s opening stroke, the remaining air will exhaust thru the cushioning orifice. How much cushioning depends on the cushioning adjustment.

Vapor, motor, differential
Cushioning adjustment controls the doors from slamming open.

 

 


 

Adjustment:

Door motor adjustments should be performed with a minimum of 90 psi. to get the proper adjustment speeds.
The required cycle time for opening or closing of doors is 2.5 to 3 seconds.
Always start with closing speed, since this affects the door opening speed.
All door hardware must be checked for wear or binding before motor adjustments are performed.
Wear eye protection.

Caution: Adjustment screws are not captive, and if they are unscrewed to far out with air pressure, they can become projectiles. 

 

Tools:

⇒ 5/32 Allen wrench
⇒ Flat blade screwdriver
⇒ 1/2 Wrench

Adjustments should be done in the following order:

Vapor, Closing speed, opening speed, cushion adjustment
Vapor differential motor adjustment order

1. Closing Speed: Loosen closing speed jam nut and use 5/32 Allen wrench to adjust closing speed.
Turning screw in (clockwise) will decrease closing speed.
Turning screw out (clockwise) will increase closing speed.
Closing speed should be approximately 2.5 – 3 seconds. After adjustment is done tighten jam nut, recheck closing speed.

 

2. Opening Speed: Loosen closing speed jam nut and use 5/32 Allen wrench to adjust opening speed.
Turning screw in (clockwise) will decrease closing speed.
Turning screw out (clockwise) will increase closing speed.
Opening speed should be approximately 2.5 – 3 seconds. After adjustment is done tighten jam nut, recheck opening speed. Disregard door slamming when opening, cushion adjustment will control this.

 

3. Cushion Adjustment: Loosen cushion adjustment jam nut and use flat blade screwdriver to adjust cushion speed to prevent door from slamming open.
Turning screw in (clockwise) will decrease dampening speed.
Turning screw out (clockwise) will increase dampening speed.
The cushioning adjustment is designed to affect the last quarter of the door travel on the opening cycle only. Opening speed may have to be readjusted to get the best combination of opening speed and cushion adjustment. Once adjustment is done, re-tighten cushion jam nut.

Recheck closing, opening and cushion adjustment. Check that all jam nuts are tight.

Allison WTEC III & Gen 4 / 5 Hardware Differences

 

Facts:

WTEC I,II,&III series – Late 1990’s discontinued after Gen 4 around 2006
Gen 4 – July 2005
Gen 5 – December 2012
GM sold Allison – August 2007 for 5.6 billion.
Allison 1000/2000 are the Chevy/GMC Duramax that are light duty transmissions.
Allison 3000/4000 are the medium and heavy duty transmissions used in transit buses.
⇒All of the Gen 4 and up Allison transmissions use the same TCM.
Allison DOC will troubleshoot all versions of Allison transmissions.
Allison Gen 4 / 5 require an electrical break out box to troubleshoot transmissions.
⇒The difference between Gen 4 / 5 is a newer style TCM and Shifter, mechanically same.
⇒Latest Version is Allison DOC 14.0

 

 


 

 

Specs:

 B400R                 3000 Series
B = Bus / R = Retarder
This Transmission is mainly used in 35 ft, 40ft, and 45 ft. buses. The retarder is a hydraulic
braking system used to help slow the bus down to save on brake wear.

 

Versions:
WTEC III (Discontinued, but service and parts are available)
Gen 4
Gen 5

 

⇒Weight: 700 lbs.
⇒2” shallow sump
⇒26 quarts total (excluding external components)
⇒16 quarts service fill (drain and filters)
⇒Torque converter ratio –  4:18

 


Transmission Ratios
1st – Range: 3.49 : 1
2nd – Range: 1.86 : 1
3rd – Range:  1.41 : 1
4th – Range:  1 : 1
5th – Range:  0.75 : 1
6th – Range:  0.65 : 1
Reverse – 5.03 : 1

 

 

Transmission Identification (TID)
WTEC III: TID 3

Gen 4: TID A
Gen 5: TID A
Note: ECU/TCM TID must match transmission harness TID to operate.

 

 

B500R                  4000 Series
B = Bus / R = Retarder

This Transmission is mainly used in 60 ft. articulated buses. The retarder is a hydraulic
braking system used to help slow the bus down to save on brake wear.

 

⇒Weight: 950 lbs.
⇒2” shallow sump
⇒43 quarts total (excluding external components)
⇒30 quarts service fill (drain and filters)
⇒Torque converter ratio –  5:21

 

Versions:
WTEC III (Discontinued, but service and parts are available)
Gen 4
Gen 5


Transmission Ratios
1st Range: 3.51 : 1
2nd Range: 1.91 : 1
3rd Range:  1.43 : 1
4th Range:  1 : 1
5th Range:  0.74 : 1
6th Range:  0.64 : 1
Reverse:   -4.80 : 1

 


Transmission Identification (TID)
WTEC III: TID 3

Gen 4: TID A
Gen 5: TID A
Note: ECU/TCM TID must match transmission harness TID to operate.

 

 


Clutch Combinations and Planetaries:
B400R / B500R
WTEC III, Gen 4 and Gen 5 all have the same clutch combinations. They all also use three planetaries P1, P2 and P3.
Allison, B400R, B500R
Allison B400R / B500R Cut Away


Note: B400R and B500R have the same layout for clutches and planetaries.

Neutral:       C5
Reverse:     C3 – C5
1st Range:  C1 – C5
2nd Range: C1 – C4
Lock Up =   LU
2nd Range: C1 – C4 – LU
3rd Range: C1 – C3– LU
4th Range: C1 – C2– LU
5th Range: C3 – C2– LU
6th Range: C4 – C2– LU

 


Solenoid to Clutch:
B400R / B500R
WTEC III and Gen 4 / 5 have different solenoid to clutch combinations and the shift valve bodies are completely different.

Allison, WTEC III Valve body
Allison WTEC III Solenoid to Clutch Combinations
Allison, Gen4, Gen5, Valve body
Allison Gen 4 / 5 Solenoid to Clutch Combination

ECU / TCM Types:
Allison ECU / TCM types vary with models. Verify ECU / TCM by checking the Calibration Identification Number (CIN) on the ECU / TCM tag to match the unit being replaced. If tag is missing or damaged, connecting the ECU / TCM to Allison DOC software will display the CIN number. Verifying the CIN number is the best way to assure the correct ECU / TCM is being installed into the vehicle, since mix up do occur.
Allison, WTEC III, Gen 4, Gen 5, ECU, TCM
Allison ECU / TCM Types

 

Allison DOC CIN Numbers Identify Program in ECU / TCM
Allison DOC CIN Numbers Identify Program in ECU / TCM

 

 


Allison Shifters:

Allison shifters completely differ between WTEC III and Gen 4 / 5, and are not interchangeable between versions. Gen 4 / 5 shifters are interchangeable between those two versions.

Allison, Shifter, WTEC III, Gen 4, Gen 5
Allison Shifters

 

 


Allison Valve Bodies:

Allison valve bodies between WTEC III and Gen 4 / 5 differ greatly in electronics and hydraulic flows.

Allison, B400R, WTEC III, Valve body
Allison B400R WTEC III Valve Body

 

allison, B400R, Gen 4, Gen 5, Valve body
Allison B400R Gen 4 / 5

 

Allison, WTEC III, Valve body
Allison B500R WTEC III

 

Allison, Gen 4, Gen 5, Valve body
Allison B500R Gen 4 / 5

 

 


Allison B400R Integrated Cooler:

Allison B400R Gen 5 has an option to have a bolt on integrated cooler rather than a remotely mounted unit.

Allison, Oil Cooler
Allison B400R Integrated Oil Cooler

 

 


Resource Links:

Helpful resource links –
http://bustekhub.com/index.php/2016/08/02/allison-transmission-shifter-functions-and-prognostics/
http://bustekhub.com/index.php/2016/08/13/allison-transmission-filter-oil-change-b400r-b500r/
http://www.allisontransmission.com/

https://www.youtube.com/watch?v=RiMRytjuQLw