Meillerwagen - Structure

Structure

The structure of the Meillerwagen consisted of the wheeled trailer chassis, and the hydraulic lifting frame.

The trailer chassis was a lattice frame of tubular members. It comprised a transverse trunnion box member at the front, from which six longitudinal tube members ran aftward and converged into one large main central tube at the rear; the six longitudinal members were braced vertically and horizontally by smaller-gauge tubes. The rear central tube member supported a large horizontal-plane turntable. A steerable front truck was installed just behind the trunnion box member, while the turntable surmounted a two-axle rear bogey.

The steerable front truck was fitted with twin duplex wheels (four tyres), the inner wheels equipped with pneumatic drum brakes. The duplex wheels rode on swinging wishbone axles with transverse semi-elliptical leaf spring suspension. A steering lock was included for use during rear towing.

A turntable at the rear of the chassis frame supported a bogey, mounted on bearings so it could swivel and pivot. The bogey was fitted with two axles, a fixed middle axle and a steerable rear axle, both of the swinging wishbone type with transverse semi-elliptical leaf spring suspension. The middle axle was fitted with pneumatic brakes, while the rear axle was unbraked. A feedback steering system was included in the design, so that any change in direction by the rear bogey (and fixed middle axle) was duplicated by the steerable rear axle, but to twice the extent. The linkage for the feedback system was for used front towing, and was disengaged during rear towing.

The towing arm could be fitted to the front truck, or the steerable rear axle of the rear bogey. The towing arm was fitted with a sprung force stem, contrived so that the tow arm 'floated' horizontally at zero relative weight.

Each front corner of the chassis was fitted with a swing-out A-frame boom equipped with a screw jack and foot plate. The booms enlarged the Meillerwagen footprint to stabilise it during erection of the rocket, and provided a means of adjusting the Meillerwagen transverse level. The booms deployed outward and forward of the lifting frame trunnion axis to prevent it toppling forward or to either side.

The lifting frame was constructed of two formed I-beams, with tubular and box transverse braces. The lifting frame was fitted with plumbing for fuelling the rocket; wiring for powering and monitoring the rocket and for field telephones; accommodations for carrying and dismounting the rocket; and folding platforms to service the rocket with rungs to access them.

Electrics

The lifting frame was fitted with outlet sockets and wiring for field telephones. A main connection from the armoured launch vehicle switchboard to inlet sockets on the lifting frame provided circuits for four field-phone stations at the Meillerwagen – one each at the upper and lower folding work platforms and two at the launch table.

An early configuration of the Meillerwagen included hardwiring of two electrical power circuits and two FLAK-plug circuits for the power and control needs of the rocket. The system included four sockets at the upper and at the lower end of the lifting frame, and the connective wiring fixed along the starboard beam. The four circuits were connected to two Stotz ejecting plugs, stowed with their cables along the side of the lifting frame. All of this wiring had become redundant by the time the rocket attacks began, but was not removed from the Meillerwagen.

The Meillerwagen chassis was fitted with a Notek tail light at the rear, its patch plug at the front, and the connective wiring in a conduit along the chassis frame.

Hydraulics

The lifting frame erected the rocket from horizontal to vertical, using hydraulic power. The hydraulic lifting equipment consisted of a hydraulic pump and its drive motor, an oil reservoir tank, a control valve group with manometers, and the lifting pistons themselves. The drive motor was a petrol KdF (Volkswagen) 14 ps (hp) motor, adapted for stationary industrial use by the fitting of magneto ignition and a centrifugal governor as throttle; besides these modifications, the motor was otherwise identical to those found in VW Beetles, an air-cooled flat-four boxer. The motor was housed in a metal box fixed to the chassis frame. A three-piston eccentric-cam hydraulic pump was coupled to the drive motor flywheel. (Meillerwagens at Operation Backfire were fitted with electric motors as hydraulic drive in place of the petrol motor.)

A 70-litre (15 gal) oil tank was fixed to the chassis frame as hydraulic fluid reservoir.

Oil under pressure flowed from the hydraulic pump to the control valve group consisting of three valves in a common housing, manipulated via one large cross-handle and two small hand taps. The large cross-handle regulated the speed of raising or lowering the lifting frame. One hand tap selected direction to either raise or lower the lifting frame. The second hand tap controlled oil flow to the lowering piston (see below), to begin lowering of the lifting frame from its vertical position.

The two hydraulic lifting pistons each consisted of one stationary cylinder and four extending cylinders. The largest extending cylinder included a flange halfway along its length, against which hydraulic pressure could be selectively applied from either above or below; it was used during raising to delay its extension until all other cylinders had extended, and also to begin the lowering process when the lifting frame was vertical (once lowering had thus been initiated, gravity finished the job).

All components of the hydraulic system were products of Meiller-Kipper GmbH, except the KdF drive motor from Volkswagen.

Platforms

Acting as gantry, the lifting frame included a number of work platforms from which crewmen serviced the rocket. Three (later two) platforms folded flat against the lifting frame, and could be folded out from the elevated lifting frame with the use of a hand winch. Each folding platform included a safety rail of folding posts and chains.

Two side platforms or catwalks were inserted into holders for deployment on each side of the lifting frame, otherwise stowed together on brackets near the turntable. A rotating platform could be suspended from the rocket nose, to provide access to the rocket control compartments on the far side of the rocket.

The port beam of the lifting frame was fitted with around 40 rungs along its full length, with which crewmen climbed to the working platforms.

Accommodations

The lifting frame included two accommodations for the rocket, a nose clamp around the warhead and a pivoting clamp around the rocket midsection. Both accommodations included a saddle, and various mechanisms to assist dismount of the rocket onto its launch table. The mechanisms were operated with two drive shafts running up the port lifting frame beam. The drive shafts ran within the integral rungs, and were operated by a crewman with a ratchet hand tool. The two drive shafts comprised a short shaft and a long shaft; both starting at the trunnion end of the lifting frame, one running half the length of the lifting frame while the other ran the full length.

The short drive shaft operated the pivot clamp around the rocket midsection, which could move the rocket 28 mm (~1") forward or backward along its centreline. The rocket midsection was fitted with a band which included trunnion pins placed in opposition; the pivot clamp held the rocket by the trunnion pins. The pivot clamp was able to rock on a transverse shaft, thus causing the rocket to move along its centreline. After erection of the rocket to a vertical position, it was held suspended above the launch table; by use of the pivot clamp, the weight of the rocket could be gently lowered onto the launch table until fully taken up, allowing the rocket to be unsecured from the lifting frame, thus dismounting it from the Meillerwagen. The short drive shaft operated a screw sleeve, which extended to work a bell crank. The bell crank turned a transverse shaft fitted with an eccentric cam, which would push or pull the pivot clamp, thus moving the rocket forward or aftward along its centreline.

The long drive shaft ran along the full length of the port beam of the lifting frame. It entered a worm gear at the pivot clamp, then continued to the nose clamp where it entered another worm gear. A shift lever at the nose clamp disengaged the drive shaft to allow either simultaneous or independent operation of the two worm gears. The worm gear at the pivot clamp operated a pair of scissor arms, one on each side of the lifting frame to insert or extract the trunnion pins from the rocket. The worm gear at the nose clamp operated the jaws of the nose clamp to either open or close, thus enclosing or releasing the rocket.