Sprocket ZP 01.402 for Front Travel

Sprocket ZP 01.402 for Front Travel ZM-60U/90U/120U

The steering sprocket ZP 01.402 is the drive and locking component of the steering mechanism in the modernized two-wheel front travel system of the ZM-60U/90U/120U series grain loaders. In the assembly's overall kinematic scheme, it is mounted in the upper part of the strut and is responsible for steering (turning) the wheels and locking them in place. As the driven element of the chain drive, it receives torque from the operator's steering wheel and rigidly transmits it to the vertical axis of the outer fork, ensuring precise turning of the entire wheelbase. This part is structurally supplemented with a special welded steel rim that serves as the working surface for the band brake — this allows for reliable locking of the mechanism, fixing the unit's set direction of movement and preventing involuntary wheel turning caused by operational vibrations or unevenness of the threshing floor surface.

Design Features of the Sprocket ZP 01.402 for Modernized Front Travel

Structurally, the sprocket ZP 01.402 is a combined welded part, the spatial geometry of which is calculated to perform both drive and braking functions simultaneously. The base of the part consists of a flat gear ring made of reliable structural carbon steel grade 40 (Steel 40) — the use of this specific grade of steel provides an optimal balance of hardness and toughness, effectively preventing metal chipping during sudden jerks of the steering wheel or front travel. The ring has 45 working teeth (z=45), the profile of which is calculated and milled to the pitch of a standard roller drive chain for the steering column (19.05). The metal thickness of the toothed section is designed with a sufficient safety margin to withstand high torsional loads without deformation, which arise when turning the massive two-wheel base on uneven threshing floors.

The main engineering feature of this part is the presence of a steel rim, centrally welded to the sprocket face. This rim forms a circular drum with a smooth outer surface, which acts as the direct contact plane for the band brake (this is relevant for our ZM-60U/90U/120U modifications). Thanks to a high-quality welded joint, the brake ring and the gear ring work as a reliable, unified assembly — this configuration ensures smooth, precise, and intuitive locking of the steering mechanism. When tightening the brake band, the machine operator can meteredly control the force, reliably locking the unit's direction of movement and eliminating parasitic misalignment or play.

Repair Features and Replacement of Adjacent Parts for Sprocket ZP 01.402

The sprocket ZP 01.402 operates under double load conditions, acting simultaneously as an element of the steering chain drive and a support brake drum. Therefore, its natural wear or mechanical damage always requires a comprehensive inspection of the assemblies with which it directly interacts. During routine or capital repairs of the steering mechanism, it is important to check the condition of the following adjacent parts:

• Steering Drive Chain PR-19.05-31.8
  The rotation of the shaft-sprocket ZP 01.330 from the steering wheel OVI 01.022 is transmitted to the driven sprocket via the chain drive. Installing a new sprocket ZP 01.402 on an old, stretched chain is a mistake, as the disrupted link pitch can quickly wear down the new teeth.
• Shaft-Sprocket ZP 01.330
  The small drive sprocket welded to the shaft component designated as the shaft-sprocket ZP 01.330 is also subject to thorough inspection. If its teeth are worn, parasitic play will remain in the system even with a new main sprocket.
• Front Travel Brake Band ZP 01.000.1
  This band covers the welded steel rim of the part, and it is necessary to monitor the thickness and condition of the brake band and its adjacent components. If it is allowed to wear down or partially disintegrate, deep scoring can occur on the smooth surface of the sprocket rim during friction, leading to the need for further repairs and disassembly of the assembly.
• Outer Fork ZP 01.050
  This is the primary axis for mounting the sprocket, and it is important to verify the possibility of rigidly fixing the sprocket and nut on its upper surface. Loosening or wear of the mounting seats in this connection can lead to constant play, spinning, and delayed wheel base response to steering wheel turns.

Repairing the steering system always requires a comprehensive approach. If the teeth of an old sprocket have acquired a sharp shape (so-called "shark fin") or deep grooves have appeared on the brake drum, replacing only the sprocket ZP 01.402 without updating the chain PR-19.05-31.8 and the brake band ZP 01.000.1 will not yield lasting results. Only simultaneous renewal of the entire contact chain guarantees the restoration of factory precision, the absence of play on the steering wheel OVI 01.022, and reliable fixation of the unit during operation or maneuvering.

Advantages of the Updated Sprocket and Front Travel Locking Mechanism

The introduction of the modified steering sprocket ZP 01.402 at Zavod Moroza has allowed for the improvement of the front wheel travel course locking mechanism. In base versions of grain loaders from previous generations (such as ZM-60/60A), locking the direction of movement was achieved by stopping the small drive shaft-sprocket ZP 01.330 using a mechanical lock that engaged between its teeth. This approach had serious design and operational drawbacks: due to the small diameter of the part and the small leverage arm at the locking point, excessive concentrated loads were generated — this created a constant risk of deformation or shearing of the stop, or destruction of the teeth under the impact of reverse forces from the wheels during machine movement. Furthermore, the rigid pitch of the gear transmission limited adjustment precision, allowing the wheels to be set only in certain discrete positions. Serious inconveniences also arose regarding ergonomics — if, when attempting to lock the steering, the stop rested against the tooth face rather than the slot, the locking lever might not engage, and the operator had to "fish" for the necessary clearance by rotating the steering wheel, turning a simple choice of movement direction into a quite inconvenient process.

Zavod Moroza's modern engineering concept has completely eliminated these vulnerabilities by transferring the locking function directly to the large driven sprocket ZP 01.402. A special steel ring, centrally welded to its plane, performs the role of a fully functional brake drum, around which the front travel brake band ZP 01.000.1 is mounted, which is tightened via a lever drive on the frame. Incidentally, this operating principle is absolutely intuitive and understandable for service personnel, as a structurally similar and well-known band brake scheme is already successfully used in the adjacent trimmer assembly of the grain loader, located nearby on the frame.

The new solution ensures smooth, stepless, and flawlessly precise locking of the wheels at any necessary angle, without any dependence on tooth pitch. Since braking force is now distributed over a significantly larger radius of the large sprocket, physical stress in the drive chain PR-19.05-31.8 and adjacent elements has been reduced to a minimum. It is worth emphasizing that the presence of the welded steel rim in no way interferes with mounting the sprocket on classic grain loader models of previous generations. It fully maintains its previous mounting and pitch compatibility with the steering drive, providing an excellent opportunity to act in stages — to purchase and install the updated part instead of the old, worn one right now during routine repairs, and to deploy the band brake system itself later — for example, in winter, by independently modifying the assembly or ordering the necessary adjacent components.

Such an approach allows for preparing a reliable engineering base for future retrofitting with relatively small effort and without capital expenditure. Although the full realization of the new locking scheme will eventually require installing additional control elements on the frame (a lever and guides for tightening the band), the modernized sprocket ZP 01.402 is the first step that allows transitioning the steering of older machines to a modern, reliable, and ergonomic factory standard.

Production Experience and Comprehensive Solutions from Zavod Moroza

Many years of practice at Zavod Moroza prove that even the most complex operational problems of machinery can be solved through competent engineering modernization. The steering sprocket ZP 01.402 with an integrated brake drum is a prime example of this approach, where we have abandoned outdated and unreliable solutions in favor of strength, smoothness, and ergonomics. The use of high-quality structural steel, precise milling of the tooth profile, and reliable centering welding guarantee that your grain loader will respond clearly to every movement of the steering wheel and will unswervingly hold the set direction even under maximum load.

At our enterprise, you can purchase the steering sprocket as a separate part for routine repair, or order it in a package with a new chain, drive shaft-sprocket, and brake band for a capital update of the entire steering assembly. Contact our technical consultants — they are always ready to provide exhaustive information regarding part compatibility and help you choose the optimal option for restoring your machine. Our production always relies on strict geometric tolerances, impeccable welds, and the use of metal with a high calculated safety margin.

Choose reliable parts from the direct manufacturer to fully restore the working life of your grain loader and ensure its uninterrupted, stable, convenient, and maximally efficient operation for many seasons to come.