PROPELLER BALANCING KIT

TM55-4920-201-14

1.8 DESCRIPTION

pounds of weight actually suspended from the ram

piston. Engraved lines on the dial window indicate

1.9. PROPELLER BALANCING KIT

load limits for the 7A050 balancing kit's 1/16.

7A050. (See figure 1-13).

inch and 3/16-inch suspension cables. The in-

1- 10. (General. The parts comprising propeller

tegral hydraulic fluid reservoir provides for years of

balancing kit 7A050 are packed in a finished

normal service without refilling. A pump valve

hardwood, portable storage and work support case.

provides for hypassing ram pressure to the fluid

The case measures 7 x 20 x 30 inches and, when

reservoir at closely controllable rates so that

packed with all kit parts, weighs 130 pounds. The

lowering of the hydraulic ram may be done quickly

kit can be quickly assembled without any tools,

or slowly as desired. A movable lifting plate on top

and. for most applications. requires no sup-

of the ram piston provides for engaging any one of

plemental shop facilities. It consists of work stand

the suspension cable balls.

and hoist structure components (1). (2), (3), (4),

1-13. Suspension Cables and Quick-disconnect

(5), (6). (7). (9), (15), (28). and (29); a 3/16.

Coupling Assemblies.. (See figure 1-13). The

inch suspension cable (13) and quick-disconnect

3/16-inch

suspension

cable

(13),

normally

coupling (10): a 1/16-inch suspension cable

assembled to the quick-disconnect coupling (10),

(14): altcrnate hoist eye assembly (12); sup-

incorporates a series of swaged balls, any one of

plementary coupling (11); balancing arbor (23); a

which may be engaged by the lifting plate of the

handwheel assembly (26); spacers (20); and

hydraulic pump assembly. Choice of ball

adapters (17). (18). (22). and (25) for the in-

engagements provides an effective selection of cable

stallation and balance testing of propellers of SAE

lengths to accommodate the suspension of various

20 through SAE 50 spline size and for SAE flange

balancing assemblies. A second, shorter cable,

type 1, 2, 3, and 4. A spline front bushing (21) also

incorporating an alternate hoist eye assembly (12)

is provided for the installation and balance testing

and "quickie" coupling (11), may be quickly

of propellers having a cylindrical insert in place of

coupled to the end of the first cable for use with

the 30-degree front seat. Recommended maximum

regular shop hoists if desired. A third suspension

load limit for suspension of assemblies to be

cable (14) similar to the first but having a diameter

balance checked is ,550 pounds. This limit provider

of 1/16 inch, is provided for use with extremely

a large safety factor for all kit components.

light loads if desired. Its terminal fitting provides

1-11. Work Stand and Hoist. (See figure 1-3).

for assembly in quick-disconnect coupling (10) in

The work stand and hoist structure are comprised

place of the 3/16-inch cable. The quick-

of demountable components for convenient storage

disconnect coupling provides for instantaneous

in the 7A050 balancing kit storage case. When

engagement a n d d i s e n g a g e m e n t ` w i t h t h e

assembled. the two tubular legs, a circular stand

s u s p e n s i o n rod of the balancing arbor. The

casting. and the reinforced bottom half of the

coupling is so designed that, while normal no-load

storage case form the work stand upon which the

coupling and uncoupling are accomplished easily

assemblies are prepared for balancing. The work

with one hand, it cannot be disengaged under load.

stand has sufficient strength and rigidity for

1-14. Balancing Arbor (23), figure 1-13). The

supporting the propeller and helicopter assemblies

balancing arbor, upon which an assembly to be

described in this handbook with a large safety

balance checked is mounted, is of the horizontal

factor. Thc overhead hoist structure eliminates a

suspension type and features. high sensitivity and

requirement for auxiliary shop hoists in most

accuracy. The arbor is so designed that there are no

application of the balancing kit, and the offset

internal wearing surfaces; consequently, there is no

support arm provides for freedom of movement in

frictional resistance or requirement for internal

performing balancing operations and from in-

inspection, reconditioning, or parts replacement.

terference with suspended loads. The upper arm of

An integral fail-safe feature effectively prevents

the hoist structure incorporates a hydraulic pump

dropping of a suspended load in case of internal

assembly which providcs for precisely controlled

suspension failure. External load-bearing and

suspension of assemblies to be balance checked.

piloting surfaces of the arbor are nitrided. The

(12.) Hydraulic Pump Assembly (15, figure 1-

bottom end of the arbor is internally threaded to

13). The hydraulic, pump assembly contains a

receive a hand wheel assembly which supports

manually-operated pressure pump and integral

arbor loads and provides for clamping adapters and

hydraulic ram deigned for .cable suspension of

balance loads securely in position. The top end of

ads. through the hollow center of the ram piston.

the arbor suspension rod is machined for

Ram cylinder pressure is continuously indicated by

engagement with the quick-disconnect coupling. A

a load indicating gage, which calibrated in

1-15