Paragraph
General   ................................................................................................		8
Bottom carriage   ......................................................................................		9
Side outriggers   ........................................................................................		10
Leveling jacks   .........................................................................................		11
Top carriage leveling mechanism   .............................................................		12
Pedestal   ...............................................................................................		13
Top carriage   ...........................................................................................		14
Cradle   .................................................................................................		15
Equilibrators   ..........................................................................................		16
Traversing mechanism   ............................................................................		17
Elevating mechanism   .............................................................................		18
Bogies   .................................................................................................		19
Rammer   .................................................................................................		20

8. GENERAL.

a. The German 88-antiaircraft gun mount is a mobile unit carried in traveling position by two bogies (fig. 18). This gun is a dual-purpose weapon. It can be fired from the bogie wheels as an antitank weapon, or the bogies can be removed to emplace the weapon for antiaircraft fire (figs. 19 and 20). The mount consists mainly of the bottom carriage, side outriggers, leveling jacks, top carriage leveling mechanism, pedestal, top carriage, cradle, equilibrators, traversing mechanism, elevating mechanism, bogies, and rammer.

Figure 18 — German 88-mm Antiaircraft Gun — Right Side — Traveling Position

Figure 19 — German 88-mm Antiaircraft Gun — Zero-degree Elevation

Figure 20 — German 88-mm Antiaircraft Gun — Left Side View

9. BOTTOM CARRIAGE.

a. The bottom carriage is of box-section type construction, welded, and riveted. The bottom carriage is designed to form a chassis for connection to the bogies in traveling. For stability during firing, a large base area is incorporated into the design of the bottom carriage, with front and rear outriggers being integral (fig. 21). Greater stability is obtained by hinging side outriggers to the bottom carriage. The interior of the bottom carriage provides space for storing tools and accessories and for housing the electrical wiring.

Figure 21 — Bottom Carriage

b. The pedestal is bolted to the enlarged central portion of the bottom carriage. This portion also houses the handwheels used to level the top carriage. The data transmission junction box is located at the rear end of the bottom carriage (fig. 22). The gun muzzle rest for road transportation is supported at the front end. Two lugs at each end of the bottom carriage are provided to suspend the mount from the bogies. Hooks at each end of the bottom carriage are provided to engage the bogie chains (fig. 21).

Figure 22 — Rear End of Bottom Carriage

10. SIDE OUTRIGGERS.

a. The side outriggers are of the same construction as the bottom carriage, i.e., welded and riveted. They hinge to the bottom carriage and provide stability when firing in traverse other than directly to the rear or front. In traveling position, they are swung to a vertical position and secured against the mount. In firing position, the side outriggers are let down and secured in position by half-round locking pins (fig. 23). The side outriggers are provided with leveling jacks and stakes at the extremities as are the outriggers of the bottom carriage (fig. 24).

Figure 23 — Bottom Carriage Outrigger and Connecting Pins

Figure 24 — Outrigger, Showing Position of Stakes in Firing and Traveling Position

11. LEVELING JACKS.

a. The leveling jacks (fig. 25) are of a simple lead screw construction. Four leveling jacks are provided, one at the extremity of each of the side outriggers (fig. 24) and of each of the bottom carriage outriggers (fig. 21). They serve to distribute firing loads evenly when the mount is on uneven ground.

Figure 25 — Details of Firing Jack

12. TOP CARRIAGE LEVELING MECHANISM.

a. The top carriage leveling mechanism (fig. 26) is operated by handwheels in the enlarged central portion of the bottom carriage. The mechanism operates the linkages that tip the top carriage about the two centers of rotation, thereby alining the gun trunnions at a horizontal position. A level indicator is provided on the pedestal (fig. 39).

Figure 26 — Top Carriage Leveling Mechanism

13. PEDESTAL.

a. The pedestal (fig. 27) is made in three sections, namely, the pedestal, leveling universal, and traversing ring. The pedestal is of welded construction. The leveling universal is suspended in the pedestal trunnion bearings by trunnions and is tipped about the trunnions and secondary pivots. The traversing ring is bolted directly to the top of the leveling universal. The pedestal is bolted to the bottom carriage and supports the top carriage.

Figure 27 — Components of Pedestal Assembly

b. An adjustable azimuth scale is provided for the orientation of the weapon. The leveling universal houses the self-alining roller bearing gimbal and ball thrust bearing on the pintle of the top carriage (fig. 28).

Figure 28 — Pintle and Bearing Arrangement

14. TOP CARRIAGE.

a. The top carriage (fig. 26) is of welded construction. The forged hollow pintle is welded to the top carriage and houses the data transmission cable. The top carriage rests directly on the leveling universal of the pedestal and is kept in place by the gimbal bearing. The nut at the end of the pintle (fig. 28) prevents any vertical motion.

b. The cradle trunnion housings, azimuth and elevation mechanism housings, direct sight elevating housing, and equilibrator trunnion supports are all welded to the top carriage. The leveling mechanism is fastened to the roller bearing at the lower end of the pintle.

15. CRADLE.

a. The cradle (fig. 29) is of rectangular-trough type section, welded, and riveted. The slides of the cradle support and guide the gun during recoil and counterrecoil. Trunnions are welded directly to the side frames and support the self-alining roller bearings. The equilibrator rod is fastened to the rear and below the trunnions by means of two clevis joined by a pin running through the cradle. The single elevating arc is fixed beneath the cradle by means of the equilibrator clevis pin and another pin just forward. Thus the arc is fastened to the cradle at two points and is readily replaced by removing the two pins. The breech operating cam and the auxiliary trigger mechanism are both fixed to the rear right side of the cradle. The loading tray is fastened to the rear left side as are the firing lever and recoil marker (fig. 14).

Figure 29 — Cradle

16. EQUILIBRATORS.

a. Two spring equilibrators are used to balance the muzzle preponderance of the gun. The equilibrators are suspended from the top carriage by trunnions and are fastened to the cradle by a clevis. In each unit there are three rectangular cross-section wire springs separated by spacers. The equilibrator rod also serves as a spring compressor and adjusting screw. Each unit is encased in a telescoping housing (fig. 30).

Figure 30 — Details of Equilibrator

17. TRAVERSING MECHANISM.

a. The traversing handwheel is located on the right side of the mount (fig. 10). The traversing mechanism may be operated in either high or low speed. For changing from one speed to the other, a gear selector lever is provided at the handwheel (fig. 31).

Figure 31 — Traversing Limit Indicator

b. A 360-degree traverse is permitted by the traversing ring. An indicator, located above the traversing handwheel, shows when the mount has made up to two complete revolutions in either direction (fig. 31). A Belleville spring stop at the left side of the top carriage prevents rotation in excess of two complete turns in any one direction. This is to prevent tangling of the data transmission cable. The azimuth data transmission indicator is geared directly to the circular rack just above the traversing ring.

18. ELEVATING MECHANISM.

a. The elevating handwheel is located on the right side of the carriage (fig. 10). Motion is transmitted from the handwheel, through gears, to the elevating pinion which engages the elevating rack, thereby elevating or depressing the gun. The elevating mechanism may be operated in either high or low speed. For changing from one speed to the other, a gear selector lever is provided at the handwheel similar to the one on the traversing handwheel.

b. A clutch (fig. 32) is provided as a means of disengaging the elevating mechanism (fig. 10) from the elevating arc to prevent transmission of road shocks to the elevating gear system during traveling. The clutch mechanism is designed to prevent excessive wear on the edges of the clutch teeth when improperly meshed. The operational design of the clutch prevents meshing until the teeth are correctly alined. The clutch alining gear is always in contact with the spur gear as the clutch fork moves the clutch body on; the central pin moves forward at the same time. The clutch teeth will not engage until this pin enters the receiving hole in the clutch alining gear. This hole is properly concentric in only one position. At this position the pin will properly seat and the clutch will engage. When both sides of the clutch engage, there is no relative rotation between the alining gear and the clutch, and the holes remain alined until the clutch is disengaged for traveling position.

Figure 32 — Elevating Mechanism Clutch Disassembled

19. BOGIES

a. The front and rear bogies are of welded construction, single axle type. The front bogie is fitted with 7-leaf transverse spring and has single wheels. The rear bogie is fitted with conventional 11-leaf suspension springs and has dual wheels.

b. The wheels are of cast spoke construction with twin detachable rims on the rear bogie and single detachable rims on the front bogie. The wheel spoke casting is fastened to the brake drum. The brake shoes are castings with the lining riveted to the outer surface. The shoes are actuated by a cam as is the practice in this country. The rims are fastened to the wheels by means of quick-release lugs (fig. 33). The lugs are loosened and then moved along the rim to bring them in line with recesses provided for the purpose and then removed. The wheels are removed from the spokes by another quick-release device (fig. 34). The release pin is pulled out until the recessed shoulder permits a quarter turn of the wheel and then the wheel may be removed by pulling straight off.

Figure 33 — Quick-release Lug

Figure 34 — Quick-release Device

c. The mount is equipped with air brakes on all wheels. The rear bogie is provided with a seat from which the hand brake lever may be operated in case of emergencies. The stop lugs (fig. 22) on the German air hose connections must be filled slightly to allow the ones on American prime movers to be inserted. At best, only a loose connection is possible, thus resulting in a leakage of air.

d. The adjustable height drawbar is fastened to the front bogie axle projection and also controls the action of the radius bars (fig. 46). The lunette on the drawbar is large enough to fit the pintle on American prime movers. The bogies are equipped to take a single tube transporter bar to connect the two bogies when removed from the mount so as to make an improvised trailer.

20. RAMMER.

a. To facilitate the loading of rounds at high angles of elevation, an automatic rammer is provided (fig. 35). This rammer is mounted on the left top of the cradle and is actuated by a hydropneumatic cylinder. The rammer head is cocked automatically during counterrecoil and is released by the action of the hand-operated loading tray.

Figure 35 — Rammer Mechanism

b. The actuating mechanism (fig. 36) utilizes gas and liquid in direct contact as in the recuperator cylinder. In this instance the cylinder is movable and the piston is fixed to the cradle. The cylinder has a removable inner liner, eccentrically located, but with its axis parallel with the axis of the outer cylinder. The system is filled with liquid to the level of the top of the inner cylinder and with nitrogen under pressure. A gas check valve is used for buffer action.

Figure 36 — Automatic Rammer Assembly

c. As the gun returns to battery in counterrecoil, a cam on the outer tube (fig. 4) engages a catch on the cylinder. The force of counterrecoil forces the cylinder forward until the gun returns to battery. At this point the cam on the tube is disengaged and the loading tray interlock prevents the cylinder from returning the position. The motivating force for ramming is now the mixture of liquid and gas under pressure.

d. As the cylinder moves forward with the gun in counterrecoil, the rack and pinion linkage (fig. 36) actuates the ramming arm in the opposite direction. Thus, when the gun is in battery and the cylinder fully cocked, the ramming arm is fully extended and the mechanism is in ramming position. The loading tray is hand-operated and is mounted on two supporting lugs on the left side of the cradle. When the gun is fired, the loading tray is outboard of the cradle slides, and the new round may be placed on the tray at any time. As the gun returns to battery and the rammer head is fully cocked, the round is placed in loading position by grasping the handles on the side of the tray and pushing the tray over on its pivot until the axis of the round is on the same line as the axis of the bore. At this point the loading tray interlock (fig. 14) is released and the expanding gas forces the rammer cylinder back along the piston; thus the rammer arm is rapidly withdrawn seating the round. The loading tray interlock will not permit the trigger mechanism to operate until the loading tray is returned to the outboard position. There is an "AUTOMATIC" ("AUTOMATIK") position (fig. 14) on the interlock that will permit the trigger mechanism to function automatically when the loading tray is returned to the loading position. When the interlock is on "HAND," the trigger handle must be operated manually in order to fire the piece.

e. The rammer head (fig. 36) is permitted to swivel on the rammer arm. Thus, in order to ram the round, the rammer head is returned by hand to a position in which the base of the round may be engaged. When the round is rammed, the horizontal sliding breechblock strikes the end of the head and throws it over into a position that will enable the recoiling gun to clear.

f. The rammer arm is protected in all positions by a folding guard which also serves as a guide. When the gun has been fired for the last time before preparing for a change of location, the loading tray interlock may be operated without a round in the tray, thus releasing the pressure on the rammer and permitting the end of the guard to be folded back. In order to cock the rammer before the first round is fired, a removable handle (fig. 35) is available to rotate the rack and pinion linkage and thus force the cylinder back until the loading tray interlock will take effect. From this point on, all operations are the same as previously noted.

g. At elevations above 45 degrees the air buffer operation is reduced to obtain additional energy for ramming by permitting the air to escape at a faster rate. This is accomplished by setting the buffer valve, at the front of the rammer cylinder (fig. 35), to "FAST" ("SCHNELL"). For elevations below 45 degrees, the valve should be set to "NORMAL" ("NORMAL").