B124

DESIGN: SynchroLite ~ Power Train - (for 2 engines) - Overrunning Clutch

Outside Helicopters

Groen Gyrocopter:

Sprag clutches wear out very quickly when there is no shock absorption device between them and the reciprocating engine. [~ from D.K] Particularly reciprocating engines with few power pulses per revolution. Do not use.

See; DESIGN: SynchroLite ~ Power Train - (for 1 engines) - Overrunning Clutch

Types:

See; DESIGN: SynchroLite ~ Power Train - (for 1 engines) - Overrunning Clutch

Location:

Locate between secondary reduction planet holder and mast. The clutch must be roller ramp, cam or ratchet.

Torque at location of clutch:

The torque at the overrunning clutch will be: See -

Ratios, HP, Torque & Losses:

Note the helicopter will not be flying 100% of the time at 60 horsepower, so design for 50/2 = 25 hp a side.

Sprag Clutch:

If the overrunning clutch is to be located on the input side of the second reduction then consider Torrington needle roller clutches.

Largest Torrington is 1.18" ID and 845 in-lb (70.4 ft-lb).

Cam Clutch:

Morse series B2+ and Marland-RINGSPANN R 200 series seen to be the same.

Torque Values:

 

Model

Morse Cam

Marland-RingSpann

 

206

175 lb-ft

195 lb-ft

 

207

275 lb-ft

325 lb-ft

Calculations re: Selection of Morse Overrunning Clutch (page C25)

1/ 192 to 205 to 233 ft-lb

2/ Overrunning

3/ Gradually applied 1.25 ~to~ 1.75

Note the use of a reciprocating engine and possible misalignment may take the factor up above 1.25. The fact that there is a belt in the drive train plus the inertia of the sheaves and gears etc. may minimize this factor increase.

4/ 192 * 1.25 = 240 ft-lb ~to~ 233 * 1.75 = 407 ft-lb

5/ Bore requirement is between 1.125" and 2".

6/ Overrunning speed is 600 * 1.20 = 720 RPM. Inner member is the overrunning one.

Item 0260 is 275 ft-lb. The associated bearing is taking very little load so use Ultra Light Series bearing.

Calculations re: Selection of Marland-RingSpann

Marland-RINGSPANN R 206 [Item 0524] is 195 ft-lb. 1.289" bore 2.440" OD

Requires bearing. The 206K bearing weighs 0.43 lbs.

Questions; -

What is min. and max. speed

Weight

Price

Delivery

Design & Engineering specs.

Note:- The 207 is 57% stronger (325 ft-lb) than the 206 but it, the bearing, the spacer and the larger housing OD will increase the weight by exactly 1 # per side.

 Idea

Consider moving overrunning clutch as far away as possible from planetary gears so that their 'floating' will have as little angular misalignment affect on the clutch as possible.

Warner - Sprag and Roller/Ramp Clutch:

Calculations re: Selection of Warner Overrunning Clutch (Cat P-956 8/98, page 12)

Will accept up to 0.025" of misalignment. Where did this come from?

namax = 625 RPM Maximum outer-race drive speed. OK

nimin = 400 RPM Minimum inner-race overrunning speed. OK

1/ Torque to be transmitted: (213 to 229 to 262 ft-lbs )

 

25 HP: in blue

30 HP: in green

 

229 ft-lb.

262 ft-lb.

 2a/ Reduced load cycle rate:

10^5 / (600 rpm * 60 min.) = 2.777 hours

1000 hours will be: 1000 *600 * 60 = 36,000,000 load cycles

The load factor fK is there fore 0.6875

 

= 229 * 0.6875 = 157

= 262 * 0.6875 = 180

2/ Service factor: of 1.75, for Gasoline engine and light steady load (low starting torque)

3/ Design torque:

157 * 1.75 = 275 lb.-ft. Reduction for load cycle.

229 * 1.75 = 400 lb.-ft. No reduction for load cycle.

180 * 1.75 = 315 lb.-ft. Reduction for load cycle.

262 * 1.75 = 459 lb.-ft. No reduction for load cycle.

4/ Shaft size: 1.375" diameter or less; which is less than the bore of all for clutches.

5/ Overrunning speed: 600 rpm * 1.2 = 720 rpm. (Inner race)

6/ Selection:

Model:

Torque capacity:

Bore:

Weight:

AS-40

168 lb.-ft.

1.57"

0.86 lb.

AS-45

196 lb.-ft.

1.77"

0.97 lb.

AS-50

210 lb.-ft.

1.97"

1.08 lb.

AS-55

280 lb.-ft.

2.17"

1.46 lb.

ASK-60

295 lb.-ft.

2.36"

1.10 lb.

Ratchet Clutch:

This will be used if;

1/ roller ramp overrunning clutch advances around mast during use, or

2/ accurate positioning of azimuth is required.

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Last Revised: February 8, 2005