TM  1-1520-240-10            4-3-1 SECTION  III.  CARGO HANDLING SYSTEMS 4-3-1.  Winch/Hoist System. A  3,000-pound-capacity  hydraulically  operated  winch (fig. 4-3-1) is mounted on the floor in the right forward cabin at sta 120. Hydraulic power to operate the winch is supplied by the utility hydraulic system. The winch (fig. 4-3-2) has 150 feet of usable 1/4 inch cable. It is capable of winching up to 12,000 pounds of cargo with the aid of pulley blocks. When used in hoisting mode (fig. 4-3-9), the load is limited to  600 pounds. The winch has two maximum reeling speeds: one for cargo loading (20 fpm) and one for hoisting (100 fpm). When the winch is used for cargo loading, a selector control lever on the cable drum housing is moved to CARGO. When the winch is used for hoisting the selector control lever is moved to RESCUE.  A  mechanical  braking  devise  automatically locks the cable drum when power is off, preventing loss of load control through cable payout. If the winch cable load exceeds 3,200 pounds, an overload switch will au- tomatically  stop  the  winch.  The  free  end  of  the winch cable is equipped with a metal ball which locks into one end of the quick-disconnect devise that is used to attach hooks to the cable. Both ends of the cable are painted red for  20  feet  to  alert  the  operator  that  the  cable  end  is approaching. In CARGO mode, the winch will automati- cally stop when the cable is reeled out 150 feet, and at 3 feet when the cable is reeled in. In RESCUE mode, the winch will stop when the cable is reeled out 150 feet and at 28.5 feet when the cable is reeled in. 4-3-2.  Winch Controls. The winch can be controlled from the cockpit by switches on  the  overhead  switch  panel  (fig.  4-3-3)  or  from  the cargo compartment by switches on the winch/hoist con- trol   grip.   The   switches   in   the   cockpit   override   the switches on the control grip, enabling the pilot to assume control of the hoisting operations in an emergency. When operating from the cargo compartment, the winch-hoist control grip can be plugged into a receptacle on the auxil- iary control panel (fig. 4-3-4) at sta 95, the hoist operators panel at sta 320 (fig. 4-3-8), or the receptacle at sta 502 (fig. 4-3-5) by an extension cord. The winch can also be manually operated from the cabin. These controls are for emergency use only. The controls are mounted on the structure  in  the  heater  compartment.  Instructions  for manual operation of the winch are on the structure above the control valves and instructions in this section. Electri- cal power to operate and control the winch is supplied by the 28-volt No. 1 DC bus through two circuit breakers on the No. 1 PDP. These two circuit breakers are marked HOIST CABLE CUTTER and HOIST CONT. NOTE The   cable   cutter   arming   devise   must   be plugged into the receptacle on the auxiliary control  panel  at  sta  95  (fig.  4-3-4)  and  the cable speed selector lever must be at CAR- GO to complete the winch control circuit for cargo operations. The cable cutter arming de- vise must be plugged into the receptacle on the  overhead  above  the  utility  hatch  (fig. 4-3-6)  and  the  cable  speed  selector  lever must  be  at  RESCUE  to  complete  the  hoist control circuit for hoisting operations. a. Winch  control  switched  (overhead  switch  pan- el). (1) Hoist master switch. A toggle hoist master switch is on the hoist control panel (fig. 4-3-3). The switch (labeled HOIST MSTR) has positions marked REMOTE, OFF, and PLT. When the switch is at REMOTE, electrical power from the 28-volt No. 1 DC bus, through the HOIST CONT circuit breaker, energizes the winch arming switch on  the  winch/hoist  control  grip.  Once  this  switch  is pressed, the winch cable switch, also on the grip, is ener- gized, allowing the winch reeling speed to be controlled at the hoist operator’s station. When the master switch is at PLT, electrical power energizes the hoist control switch on the overhead switch panel, which gives the pilot con- trol of the hoisting system. When the switch is at OFF, power is removed from the hoist control switches at both stations. (2) Hoist control switch. A spring-loaded, rheo- stat-type switch is provided for hoist control and is on the hoist control panel. The switch (labeled HOIST) has posi- tions marked OFF, IN, and OUT. When the hoist master switch is at PLT, electrical power, from the 28-volt No. 1 DC bus through the HOIST CONT circuit breaker, ener- gizes the hoist control switch. Then the switch is moved to IN or OUT, the hoist brake release solenoid valve is energized open. The open valve applies hydraulic pres- sure through the hoist control valve to the winch to turn the cable drum in the appropriate direction. The speed of the cable is proportional to hoist control switch move- ment. When the switch is released, the switch assumes the center OFF position. In addition, the brake release solenoid  valve  is  deenergized  closed,  which  removes hydraulic pressure to brake the cable drum.