Source: https://balanceandtest.com/resources/horizontal-vs-vertical-balancing-machines/ - **Horizontal vs Vertical** Ask an Engineer - [Home](https://balanceandtest.com/) - [Resources](https://balanceandtest.com/resources/) - Horizontal vs Vertical Balancing Machines Balancing guide # Horizontal vs Vertical Balancing Machines Horizontal machines balance rotors that have their own shaft. Vertical machines balance disc-shaped parts on a spindle. How to tell which suits your part. Read the guide Ask an Engineer Contents - Horizontal balancing machines - Vertical balancing machines - Side by side - Does vertical mean static and horizontal mean dynamic? - How to decide Written by [Steve Fowler](https://balanceandtest.com/about-us/steve-fowler/) , Managing Director, Balance & Test. 35+ years in rotor balancing; project manager for the rewrite of ISO 21940-21. **Short answer:** The names describe which way the rotor's axis points on the machine. A horizontal machine supports a rotor lying on its side, on its own journals. A vertical machine holds a disc-shaped part flat on an upright spindle. The right choice follows from one question: does the part have its own shaft? ## Horizontal balancing machines The rotor lies on its side and rests on two supports, usually rollers, at its own bearing journals. It is driven either by a belt running over the rotor body or by an end drive: a jointed drive shaft coupled to one end. Belt drive adds nothing to the part, so it is the first choice where there is a clean surface for the belt. End drive is for heavy rotors, fans with high windage and parts with nothing to put a belt on. **Suits:** rotors with their own shaft or journals. - Electric motor armatures and rotors - Crankshafts and driveshafts - Rolls, spindles and turbine rotors - Fans and impellers already mounted on their shaft ### Strengths - The rotor runs on the same journals it will run on in service, so no tooling error is added. - The supports slide along the bed, so one machine covers a wide range of lengths and weights. - Two-plane measurement is standard. ### Limits - A part with no shaft needs a balancing arbor made for it, and the arbor's own error has to be dealt with. - Loading long or heavy rotors needs a crane or lifting gear and floor space along the bed. ## Vertical balancing machines The part sits flat on a spindle that points upward, located by its bore or a register and held by a chuck, collet or fixture. The spindle spins the part. **Suits:** disc-shaped parts with no shaft of their own. - Flywheels, clutches and pressure plates - Brake discs and drums - Pulleys, gears and grinding wheels - Fan wheels and pump impellers before they're fitted to a shaft ### Strengths - Fast to load and unload: the part drops onto the tooling, which also makes automatic loading easy. - Correction by drilling or milling can be built in at the same station. - Small footprint. ### Limits - The tooling carries the accuracy. Run-out or looseness in the adapter shows up as unbalance in the part, so tooling has to be made well and checked. A 180° index test (measure, turn the part half a turn on the tooling, measure again) tells you how much is tooling. - Each bore size or part family may need its own adapter. ## Side by side | Specification | Horizontal | Vertical | | Rotor axis | Lying flat | Upright | | Part held by | Its own journals, on rollers or bearings | Tooling on the machine spindle | | Typical parts | Shafts, armatures, crankshafts, rolls | Discs, flywheels, brake discs, pulleys | | Planes | Usually two | One or two | | Loading | Lifted onto supports | Dropped onto spindle | | Main source of error to manage | Drive and journal condition | Tooling run-out | A horizontal machine carries the rotor on its own journals; a vertical machine carries a bored part on tooling on its spindle. ## Does vertical mean static and horizontal mean dynamic? No. Many vertical machines measure in two planes, and a horizontal machine can be used for a single-plane correction. Orientation is about how the part is held. The number of planes is a separate question, covered in [static vs dynamic balancing](https://balanceandtest.com/resources/static-vs-dynamic-balancing/) . One more distinction: **hard-bearing** and **soft-bearing** machines. A hard-bearing machine has stiff supports that barely move, so it measures force and stays calibrated for any rotor within its range; you set the dimensions and run. Most of our machines are hard-bearing. A soft-bearing machine lets the supports move and measures that movement. It is very sensitive but needs a trial run on each new rotor type. Driveshaft machines are usually soft-bearing. ## How to decide - **Does the part have its own journals?** Yes: horizontal. No: vertical. - **Is it a disc that will later be fitted to a shaft?** Balance it on a vertical machine as a component. If the assembly tolerance is tight, balance the finished assembly on a horizontal machine as well. - **What volume?** High-volume disc parts favor vertical machines with automatic correction. - **How long and heavy?** Long rotors and heavy rotors with journals belong on a horizontal machine. Keep reading ## Related Guides and Machines Keep reading. [Machines ### Horizontal balancing machines For rotors with their own shaft or journals. View machines ](https://balanceandtest.com/balancing-machines/horizontal-balancers/) [Machines ### Vertical balancing machines For disc-shaped parts with no shaft of their own. View machines ](https://balanceandtest.com/balancing-machines/vertical-balancers/) [Guide ### How to choose a balancing machine Seven facts about your parts that decide the machine. Read the guide ](https://balanceandtest.com/resources/how-to-choose-a-balancing-machine/) [Guide ### Static vs dynamic balancing One plane or two, and which your rotor needs. Read the guide ](https://balanceandtest.com/resources/static-vs-dynamic-balancing/) Questions about your rotor? ## Horizontal or Vertical? Send us the drawing and tell us whether the part has its own journals, and we will recommend the machine. UK +44 117 405 4011 USA +1 616 377 1077 [Email info@balanceandtest.com](mailto:info@balanceandtest.com) Ask an Engineer