The gear reducer mounting position is technical information that defines how the unit is oriented in space during operation; in other words, the angle of the input and output shafts relative to the ground. In catalogues, it is usually shown with short codes such as B3, B5 and V1, and it is a parameter that directly determines whether the gear reducer will be lubricated correctly.
The importance of this information may not be obvious at first, but an incorrectly selected position opens the door to a chain of problems. When the oil inside the housing collects at a point different from the designed one, the gears cannot be lubricated sufficiently, friction increases, the housing heats up and early failure becomes inevitable over time. In short, the mounting position is a silent but decisive factor in the service life of a gear reducer.
In this guide, we explain step by step exactly what the mounting position means, which code corresponds to what, how it affects lubrication and why it must be specified when placing an order.
What Is a Mounting Position and Why Is It Important?
The mounting position describes in which direction and at what angle the gear reducer housing stands during operation. Details such as whether the feet rest on the floor, which surface the flange is connected to, whether the motor remains on top or on the side, and whether the shaft points upward or downward are all included in this definition. If you are curious about the internal structure and basic operating logic of a gear reducer, what is a gear reducer page makes this topic easier to understand.
The point where this information is most decisive is the oil level. The gears and bearings inside the reducer operate thanks to the oil bath in the housing. A gear group that is correctly lubricated when the housing is horizontal may be left without oil when the same reducer is mounted vertically because the oil collects at the bottom. For this reason, the manufacturer defines a separate oil level, oil plug and breather point for each mounting position.
Heat dissipation also depends directly on the position. In a horizontal layout, the housing surface dissipates heat over a wider area, while in a vertical layout the heated regions may differ. In a reducer operating continuously at high temperature, the oil properties deteriorate, seals harden and gear life becomes shorter. This is why the mounting position must be clearly specified in the catalogue and in the order; even if the power and speed values are correct, field performance drops if the position is wrong.
Gear Reducer Mounting Position Codes and Their Meanings
To standardize mounting positions, the industry uses a letter- and number-based coding system. These codes are divided into two main groups: horizontal positions, where the housing is parallel to the ground, are indicated with the letter B; positions where the shaft operates on a vertical axis are indicated with the letter V. The table below summarizes the most common codes and their typical areas of use.
| Code | Position / Type | Typical Use |
|---|---|---|
| B3 | Horizontal, foot-mounted (standard) | Most common option; mounting on the floor or foot base |
| B5 | Flanged connection | Direct mounting to the machine via the flange |
| B35 | Foot-mounted + flanged | Systems requiring both support and flange connection |
| B6 / B7 / B8 | Side / wall / inverted horizontal | Positions with limited installation space |
| V1 | Vertical, shaft downward | Vertical drives such as mixers and pumps |
| V5 / V6 | Vertical variations | Application-specific vertical mounting |
The values here are for general information. The exact position suitable for your application must be confirmed according to the catalogue of the relevant model. Now let us examine these two groups a little more closely.
Horizontal (B) Mounting Positions
Horizontal mounting is the arrangement in which the reducer housing is parallel to the ground and is preferred in many systems such as conveyors, belts and mixers. In this group, different codes are used according to the connection type:
- B3: The housing is mounted on its feet so that it rests on the floor. It is the most common and default position.
- B5: The reducer is connected directly to the driven machine from the flange surface and does not require a separate foot base.
- B35: It is a solution used in systems where foot mounting and flanged connection are both present and extra support is required.
- B6, B7, B8: These are positions in which the housing is mounted to a side surface, a wall or in an inverted direction, and they are generally used where space is limited.
Vertical (V) Mounting Positions
In vertical mounting, the housing stands upright and the shaft operates on a vertical axis. This arrangement becomes essential especially in agitators, vertical mixers and some pump applications:
- V1: The output shaft is positioned facing downward; it is frequently used in mixers and pumps that require vertical drive.
- V5 and V6: These are application-specific vertical variations in which the shaft faces upward or operates in different directions.
The common feature of vertical positions is that they require a more careful lubrication plan because the oil tends to collect in the lower region. In such applications, manufacturers often provide an additional oil reservoir or supporting lubrication solutions.
Effect of Mounting Position on Lubrication and Oil Level
Quiet operation without overheating in a gear reducer depends largely on lubrication. When the mounting position changes, the region where the oil collects inside the housing also changes; this directly affects the locations of the oil filling, level and drain plugs. A level plug located correctly on a horizontal reducer may correspond to the wrong point when the same housing is mounted vertically.
The ventilation plug, namely the breather, is also affected by this change. The breather’s task is to balance the pressure inside the housing as it heats up during operation. A breather left in the wrong position both disrupts pressure relief and may cause oil leakage from that point. Therefore, for each mounting position, the breather and the filling and drain plugs must be located on the correct surface.
Additional precautions come into play in vertical mounting. The tendency of oil to collect in the lower area increases the risk that the bearings and gears in the upper parts may not be lubricated sufficiently. Therefore, in vertical applications, solutions such as an additional lubrication arrangement, different seal selection or a supporting oil reservoir are preferred. When determining the model suitable for your application, we recommend that you do not skip the gear reducer selection stage.
The oil change interval and maintenance period are separate topics; you can follow these details in our related oil and maintenance content. The main point to emphasize here is that the correct position establishes the lubrication arrangement properly from the beginning and also determines maintenance convenience.
Why Must the Mounting Position Be Specified When Ordering?
When the mounting position is not specified at the ordering stage, the reducer is usually manufactured assuming the standard B3 position. This does not cause a problem for a horizontal foot-mounted application, but if the system will operate vertically or with a flange, the plug and lubrication arrangement is set up incorrectly from the start. On the reducer arriving at the site, the breather remains on the wrong surface, the oil level does not match and the installation has to be revised.
Such a revision means loss of both time and cost. However, when the shaft direction, motor position and housing orientation are clarified before ordering, the reducer is manufactured with the correct plug arrangement and oil level. This speeds up installation and provides healthy performance from the first start-up.
In short, position information is an order parameter as important as the technical values. To clarify the most suitable mounting solution for your application, you can consult the Remak Redüktör technical team at the project stage and prevent possible revisions by sharing the shaft direction and position details from the beginning.
What Problems Does an Incorrect Mounting Position Cause?
What truly shows the importance of the correct position is the failures caused by the wrong choice. Many problems encountered in the field stem from a reducer being mounted at an angle different from the one specified in the order. The first sign of such situations is often excessive heating; insufficiently lubricated gears increase friction and the housing temperature rises rapidly.
The second common problem is oil leakage. When oil accumulates at a point different from the designed one, it applies continuous pressure to the seals and leakage starts over time. This is usually followed by early gear wear, because metal-to-metal contact occurs in areas where the oil film remains thin and the gears wear out prematurely. The same chain also shortens the life of bearings exposed to uneven loads.
The common feature of these symptoms is that they appear over time, not at the moment of installation. Although the reducer may seem trouble-free when first installed, the wrong lubrication arrangement reveals itself within weeks as noise, vibration and efficiency loss. To compare how different reducer types react to position and to see the model suitable for your application, you can review the products page’s helical gear, planetary gear and worm gear reducers groups.
Get an Offer for the Right Gear Reducer and Mounting Solution
To determine the mounting position and reducer model suitable for your application, the technical calculation must be made together with the position information. You can evaluate power, speed and torque values with the gear reducer calculation tool, and for any points you are unsure about, Remak Redüktör contact you can request an offer through the page and decide on the right solution together.
Frequently Asked Questions About Mounting Positions
Which code is used for standard production when no special connection direction is specified?
If no special position is specified, reducers are generally manufactured assuming the standard B3 (horizontal, foot-mounted) position. If your application is vertical or flanged, this can cause incorrect plugging and lubrication problems, so if you have a special angle, the safest approach is to notify it before manufacturing.
Can the gear reducer mounting direction (position) be changed later in the field?
Only to a limited extent, and not in every model. A position change requires the oil level, plug locations and sometimes the seal arrangement to be readjusted. Therefore, if a change is being considered, it must be done with manufacturer confirmation and technical support.
How should ventilation (breather) plugs be adjusted when the mounting angle changes?
The breather’s task is to balance the pressure inside the housing, and for it to work correctly it must always remain at the highest point of the housing. When the reducer angle or position changes, the breather location must also be redefined according to the new top point to prevent oil leakage.
Are there bidirectional reducer models that can operate on both horizontal and vertical axes?
Although some models are manufactured to suit different positions, this is not an automatic feature. If a reducer prepared for horizontal use is operated vertically without modification, the lubrication arrangement may be insufficient. If bidirectional or variable-angle use is required, this must be confirmed according to the catalogue of the relevant model.
Does the oil capacity (litres) differ between horizontal (B) and vertical (V) connection directions?
Yes, it differs directly. The required oil volume and level inside the housing change according to the operating position. A reducer with the same housing structure may require different litres of oil in horizontal and vertical positions; the correct quantity must be verified from catalogue data.
