04 sistem puli dan tali
TRANSCRIPT
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MS 416 Pesawat angkat
,
Tito Shantika, Meng
Mechanical Engineering Department
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Komponen pesawat angkat pada
umumnya:
Perlengkapan Pengangkat Fleksible (misal Tali kawat
baja) Puli, Sistem puli, sproket dan Drum
Alat Penghenti (Rem)
Motor Pen erak
Sistem Transmisi (poros, bantalan, kopling dansebagainya)
e an a au ro a penggera Struktur atau rangka pesawat angkat
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Sistem uli
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Sistem Pull –Drums
W → berat beban & berat lower
block,
P → gaya pada winding drum
μ → loss coefficient.
Pada saat turun
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Part line
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Ro e forceIf n is taken as the number of parts of line supporting the load and m is the number of
180° turns taken by the rope between the upper block and the drum (turning angles
for each of the sheaves are added to find the number of 180° multiples), then
raising the load:
lowering the load:
s mp e
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Friction coefficient
4½% of rope load for a sheave mounted onbronze bushings to a low of as little as 0.9% for a
sheave on precision ball or roller bearings.
An arbitrary value of 2% is a reasonableapproximation for sheaves on common ball or roller
bearings when the rope makes a turn of 180°.
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exam le
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exam le
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exam le
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DRUMS AND SHEAVES
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Drums
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Fleet an le
When using a pivoted block, one must be sure that it is set close enough to
the drum to provide at least 1 ⁄ 2° of fleet angle in the maximum layover
pos t on. oo sma a eet ang e w cause t e wraps to p e up at t e ange
(particularly at low loading levels), whereas an adequate angle will guide
the rope away from the flange.
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Drum ca acit
-L→ is drum capacity [feet ]
- ,
-the spooling factor (s) → is taken from Table 1.1 or
calculated
- d → as the actual rope diameter.-Table 1.1 assumes new rope and includes a rope
diameter oversize factor of 5%.
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S oolin factor
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maximum uantit of ro eThe first case involves the maximum quantity of rope
a can e s ore on a rum w en e o s s no n
operation. Dimension C is taken as zero (Maxcapascity
The second case is used to determine the
maximum uantit of ro e that can be s ooled
onto the drum of an operating winch. C is taken
as ½ in (12.7 mm) or preferably as one rope
diameter, and
The third case is used to estimate the quantity
of rope found on a drum.
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Line PullHoist drums are rated b line ull the tension the drum is ca able of a l in to a
rope leading onto it) and by line speed.
T→ rated torque
r→ ne pu on e rs ayer,
D→ Dia. Drum
d → rope diameter.
for a system with nominal rope diameter d and with consistent dimensional units. The
usable line pull Pu
at any other drum layer is found from
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drum s eedω
& line s eed V
t e rum spee ω in revo utions per minute is given y
ω → drum speed [rpm]
Vr → rated first-layer line speed [feet per minute]
D → drum dimensions [inches]
d → rope diameter [inches]
The line speed V u at any other rope layer
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Sheaves Sheaves are used to chan e the direction of travel of wire
ropes. Assembled in multiples, in the form of blocks, they are
able to provide almost any required mechanical advantage.
Sheaves rotate about their mounting sha ts on bushings or
bearings. A reasonable value for friction loss at bushings can
be taken as 41 ⁄ 2%, while bearings produce losses of 1% to2%, depending upon their quality and the conditions of
service. These losses are rough average figures for ropes
°
for smaller turning angles. Actual friction losses are a function
of the style of rope, the ratio of sheave to rope diameter, and
t e earing type.
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Service life
curve
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The ratio of the relative ro e lives Lr
where r1 and r2 are the D/d ratios being compared and Lr is the ratio
of the relative rope lives.
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Blocks
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TERIMAKASIH