300C Fan, Pulley and Fan Clutch Use

["Wayne Graefen" <wgraefen@xxxx>]

This should help the fan, pulley and fan clutch questions for the 300C. There were changes made during production. I hope the formatting holds up for your legibility. 



Without power steering, a single groove 5 11/16" O.D. pulley is used. With PS but no air conditioning, a double groove 6.5" OD pulley is used. With AC, a 7.125" pulley is used.



The following information is from Chrysler Engineering Tech Report # 4406.522 regarding the cooling fans and fan clutch used on the 300C. Info is from p. 4-5 and p. 8 of the report.



Wayne


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Fan - Standard 300C



Initial Release

Fan Part Number 1735939

O.D. 18 inches

Number of Blades - 4

Projected width 1-3/4 inch

Drive - Direct (0.95:1 speed ratio)



Intermediate Change

Fan Part Number 1735941

O.D. 18 inches

Number of Blades - 6

Projected width 1-7/8 inches

Drive - Schwitzer (1.1:1 S.R.) Part No. 1851603



Final Change

Fan Part Number 1851604

O.D. 18 inches

Number of Blades - 5

Projected width 2 inches

Drive - Schwitzer (0.95:1 S.R.) Part No. 1851603



Fan - Air Conditioning



Initial Release

Fan Part Number 1555784 Spider type

O.D. 18 inches

Number of Blades - 6

Projected height 1-7/8 inches

Drive - Direct (0.95:1 S.R.)



Intermediate Change

Fan - See above Part No. 1735941

Drive - Direct (0.95:1 S.R.)



Final Change

Fan - See above Part No. 1851604

Drive - Schwitzer (1.10:1 S.R.) Part No. 1851603


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7. Fan and Fan Drive Evaluations



Fan and fan drive evaluations are included here because of the six different combinations used throughout the production series on the 300C Standard and 300C air conditioned cars and because of the introduction of a limited slip clutch Schwitzer fan drive unit (1851603).

Initially an 18 in. O.D. 4-blade fan at 0.95:1 S.R. was put into production because the desired release 6-blade fan and Schwitzer drive (1.1:1 S.R.) were introduced together in the second or third month of production (this was the unit checked under this project). However, the 6-blade and 1.1:1 S.R. resulted in:

1. Excessive fan noise.

2. Excessive overspeed of generator (14,508 generator rpm at 5200 engine rpm, assuming no slip. Generator red line rpm is 12,000).

3. Excessive overspeed of water pump (5720 rpm at 5200 engine rpm, resulting in possible cavitation and cooling malfunction).



Consequently the final standard 300C equipment consisted of a 5 bladed fan with slightly more pitch (1851604) and a decreased speed ratio of .095:1. Air conditioned versions continued to use the 1.1:1 S.R. with the 1851604 fan, but incorporated a lower ratio generator drive. It would appear that a more comprehensive test should be made of high speed water pump effects. From Curve Sheets 33, and 34 the effectiveness of the Schwitzer Drive can be determined. The production variation of output rpm can be seen on Curve Sheet 35.

Curve Sheet 33 indicates the effect the drive has on the absolute engine output and the manner in which torque is affected. Curve Sheet 34 gives a generalized comparison between a direct drive unit at .085:1 S.R. and the Schwitzer unit at 1.1:1 S.R. The significant results of the above data are that with the Schwitzer unit:

1. Fan speed never exceeds 2300 rpm.

2. Power requirement never exceeds 6 HP.



Whereas, with direct drive, the belt drive and driven accessories can absorb power in excess of 17 BHP.

It should be noted that in the case of the direct drive, added precaution of clean and tight belts were taken to assure no belt slippage, and that this is not the actual condition in the field. However, it is possible to transmit this much power with the released belt drive.

The difference in power consumption between the two different drives at 2400 rpm (2050 fan rpm) can probably be attributed to

1. Slight differences in fan.

2. Different water pump and generator speeds.

3. Different belts and wrap.

4. Slight power consumption of Schwitzer Drive unit.









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