When F Series Torque Is Not Enough — Choosing Between ZY and H/B Series for Large Crushers

This guide is for informational purposes only. Always consult a qualified engineer for final selection.

One question we keep hearing after the F series crusher articles: “What do we do when F series torque is not enough?”

The F series parallel shaft gearmotor is the go-to solution for smaller jaw and cone crushers, with output torque up to 18,500 N·m in its largest frame size and highest torque configuration. For smaller frames, the rated torque is lower — consult the F series selection tables for your specific frame and ratio. When you move up to large jaw crushers (over 200 t/h), large cone crushers, or primary gyratory crushers, the torque demand often exceeds what a standard gearmotor can deliver.

Two paths open up:

1. ZY series – hardened helical cylindrical gear reducer, parallel shaft, built for medium-to-heavy industrial drives

2. H/B series – heavy-duty modular gearboxes, parallel shaft (H) or right-angle (B), built for the largest crusher drives

This guide explains where F series stops, what ZY and H/B each offer, and how to choose the right one for your crusher.

At a Glance: ZY vs H/B for Large Crushers

The F series parallel shaft gearmotor is an excellent solution for smaller to medium crushers. It delivers up to 18,500 N·m in its largest frame size and highest torque configuration. For smaller frames, the rated torque is lower — consult the F series selection tables for your specific frame and ratio. For jaw crushers up to approximately 150 t/h and cone crushers in the mid-range, F series with VFD handles the duty well.

The boundary is clear: When your crusher requires more than the F series rated torque for your specific frame and ratio, you have exceeded the F series capability.

At this point, you have two choices:

● Stay with parallel shaft → ZY series or H series (H2/H3/H4)

● Switch to right-angle → B series (B2/B3/B4)

The decision depends on torque requirement, space constraints, and mounting preference.

ZY Series – Hardened Helical Cylindrical Gear Reducer

The ZY series is a hardened helical cylindrical gear reducer built for medium-to-heavy industrial applications. It is available in single-stage (ZDY), two-stage (ZLY), and three-stage (ZSY) configurations.

Key characteristics:

Parallel shaft design – Input and output shafts are parallel, making ZY suitable for installations where the motor and driven equipment are aligned on the same axis. This is the same configuration as F series but scaled up.

Case-hardened, precision-ground gears – ZY series gears are case-hardened and precision-ground. This provides resistance to tooth surface fatigue from shock loads—critical for crusher applications with frequent start-stop and variable feed.

High efficiency – Single-stage efficiency reaches up to 96.5%. Two-stage efficiency exceeds 93%, and three-stage exceeds 90%.

Torque coverage – ZY series covers medium-to-high torque ranges suitable for industrial drives from small to large sizes — consult selection tables for exact ratings based on frame size and ratio.

When to choose ZY:

● Your torque requirement exceeds F series but stays within the ZY range (verify using the ZY selection tables for your specific ratio and input speed)

● You want to maintain parallel shaft configuration

● You need a cost-effective upgrade from F series without moving to modular heavy-duty gearboxes

Your crusher is in the medium-large category (e.g., 200–400 t/h jaw crushers, large cone crushers)   [2]  ZY Series vs R/F/Cyclo/GTP: Why Helical Gearbox Wins for Large Screw Conveyors

H Series – Heavy-Duty Parallel Shaft Modular Gearbox

The H series is a heavy-duty parallel shaft helical gear reducer designed for high-torque, continuous-duty applications. It is engineered specifically for environments where heavy loads, continuous operation, and punishing conditions would destroy inferior equipment.

Key characteristics:

Modular design – H series uses a modular construction with fewer component types, allowing for flexible configurations while maintaining high quality standards. Available in 1 to 4 reduction stages.

Wide torque and power coverage – H series covers torque up to 900 kN·m in parallel shaft (H2/H3/H4) configurations, and up to 290 kN·m in right-angle (B2/B3/B4) configurations. Power ratings vary by ratio and input speed — consult selection tables for exact values.

Parallel shaft configuration – Like F and ZY, H series maintains parallel input and output shafts in H2/H3/H4 configurations, making this industrial parallel shaft gearbox suitable for installations where the motor and driven shaft are aligned. This simplifies alignment in installations where the motor and driven shaft are parallel.

Right-angle option – H series (H2/H3/H4) provides parallel shaft output. B series (B2/B3/B4) provides right-angle output. Choose the series based on whether your crusher requires parallel or right-angle shaft orientation.

When to choose H series:

● Your torque requirement exceeds the practical torque range of ZY series for the required ratio and input speed (verify using the ZY selection tables)

● You need parallel shaft configuration for large crushers (primary gyratory, large jaw crushers)

● You require modular flexibility for future upgrades or modifications

Your application involves continuous 24/7 operation with high shock loads

B Series – Right-Angle Bevel-Helical Modular Gearbox

The B series is a right-angle bevel-helical gearbox product line. It uses a bevel gear first stage followed by helical stages, delivering right-angle output in an industrial bevel helical gearbox package designed for space-constrained crusher installations. B series (B2/B3/B4) is independent from H series (H2/H3/H4) — the two lines are parallel product lines within the HB series family, not interchangeable configurations.

Key characteristics:

Right-angle output – B series output shaft is perpendicular to the input, making it ideal for installations where space constraints prevent parallel shaft alignment.

Torque capacity – B series delivers right-angle output with torque capacity up to 290 kN·m. For right-angle configurations requiring torque above 290 kN·m, B series is not available — the application would require a different configuration approach.

Bevel-helical configuration – The first stage uses bevel gears to change the direction of power flow, followed by helical stages for torque multiplication.

When to choose B series:

● You need right-angle output for your crusher drive

● Space constraints prevent parallel shaft mounting

● Your torque requirement is up to 290 kN·m

You need right-angle output in a dedicated bevel-helical package

ZY vs H/B – The Decision Framework

First, determine the required output torque at the crusher input shaft. For large jaw crushers, breakaway torque is typically 150–200% of running torque. Calculate peak torque including material load and acceleration.

Next, check against the F series rated torque for your specific frame and ratio. The maximum F series torque is 18,500 N·m in the largest frame. If your required torque exceeds this, proceed to ZY or H/B selection.

Then, decide between parallel shaft and right-angle output:

● If the motor and crusher shaft are parallel → consider ZY or H series (H2/H3/H4)

● If space constraints require perpendicular mounting → consider B series (B2/B3/B4)

Then, size by torque:

→ Up to ZY series range for your selected ratio and input speed → ZY series is the most cost-effective parallel shaft choice

→ Above ZY series range for your selected ratio and input speed → H series required for parallel shaft

→ Up to 290 kN·m and right-angle required → B series is the appropriate choice

→ Above 290 kN·m and right-angle required → not available in B series; consult engineering for alternative solutions

Finally, verify thermal capacity. For large crushers operating 24/7 in hot climates, confirm that the gearbox thermal rating meets your continuous duty requirement. Cooling fans or cooling coils may be needed for high-temperature environments.

Common Mistakes to Avoid

The right approach is straightforward: Size for breakaway torque, not running torque. Know the F series rated torque for your specific frame and ratio, and step up when you exceed it. Choose ZY for cost-effective parallel shaft solutions within its rated range. Choose H series (H2/H3/H4) for parallel shaft above ZY range. Choose B series (B2/B3/B4) for right-angle up to 290 kN·m. Verify thermal capacity for 24/7 crusher duty.

Case Studies

📍 Case Study: Large Jaw Crusher Upgrade

Customer: Copper mine in Chile
Challenge: Existing F series gearmotor was overloaded on a 350 t/h jaw crusher. Torque demand exceeded the F series rated torque during start-up with full rock load. The gearmotor failed twice in 14 months.
Solution: HelmeDrive replaced the F series unit with a ZY series three-stage hardened helical gearbox. The parallel shaft configuration maintained the existing drive layout while delivering the required torque capacity.
✅ Result: No torque-related failures in 18 months. Crusher starts reliably under full load. The mine standardized ZY series for all medium-large crusher drives.

📍 Case Study: Primary Gyratory Crusher Drive

Customer: Iron ore mine in South Africa
Challenge: Primary gyratory crusher required 450 kN·m output torque with right-angle configuration due to space constraints in the crusher chamber. The original European-brand gearbox had long lead times and high maintenance costs.
Solution: HelmeDrive supplied an H series right-angle bevel-helical gearbox (B3/B4 configuration) with 450 kN·m capacity. The modular design allowed for quick installation and future maintenance access.
✅ Result: Drop-in replacement with matching mounting dimensions — no foundation modifications required. Lead time reduced by 60% compared to the original supplier.

How to Work with HelmeDrive

→ Remote video support – installation guidance and troubleshooting within your working hours

→ Torque verification – send your crusher specs and motor data; we verify torque requirements and recommend the appropriate series

→ Mounting drawings – parallel shaft (ZY/H) and right-angle (B series) available

→ Lead time – ZY series: 4–6 weeks; H/B series: 6–8 weeks; expedited options available

→ Thermal verification – we confirm thermal capacity for your specific duty and recommend cooling options if needed

Why Mines Choose HelmeDrive ZY and H/B Series

🔹 ZY series – cost-effective upgrade path from F series, parallel shaft, with torque ratings verified via selection tables

🔹 H series – heavy-duty parallel shaft (H2/H3/H4), up to 900 kN·m, modular design

🔹 B series – right-angle product line (B2/B3/B4), up to 290 kN·m, ideal for space-constrained installations

🔹 Case-hardened, precision-ground gears – resist shock loads from crusher duty

🔹 Multiple reduction stages – 1–4 stages available for optimal ratio selection

🔹 Proven in mining – widely used in crushers, mills, and conveyors worldwide

🔹 Flexible configurations – parallel shaft or right-angle, horizontal or vertical mounting

Get a Crusher Drive Selection Proposal

Send us:

◆ Crusher type (jaw, cone, gyratory, impact)

◆ Motor power and speed

◆ Required output torque (or crusher size and feed material)

◆ Preferred shaft orientation (parallel or right-angle)

◆ Site ambient temperature and altitude

◆ Duty cycle (continuous or intermittent)

📩 Sales inquiry: shawn.zhu@helmedrive.com

❓ FAQ

Q1: What is the maximum torque of the F series?
A: The F series parallel shaft gearmotor delivers up to 18,500 N·m in its largest frame size and highest torque configuration. For smaller frames, the rated torque is lower — consult the F series selection tables for your specific frame and ratio.

Q2: What torque range does ZY series cover?
A: ZY series covers medium-to-large industrial drives with torque capacity varying by frame size and ratio. Consult the ZY selection tables to verify that your specific requirement falls within the rated torque range for your selected ratio and input speed.

Q3: How do I choose between ZY, H, and B series for my crusher application?
A: Choose ZY series for parallel shaft output up to its rated torque range (verify against the ZY selection tables). Choose H series for parallel shaft output above ZY range, up to 900 kN·m. Choose B series for right-angle output up to 290 kN·m. All torque ratings vary by frame size and ratio — always consult the selection tables for your specific configuration.

Q4: Can I use ZY series for a primary gyratory crusher?
A: It depends on the torque requirement. For smaller gyratory crushers where torque falls within the ZY rated range for your selected ratio and input speed, yes. For large primary gyratory crushers requiring torque above ZY limits, H series (H2/H3/H4 for parallel shaft) is recommended.

Q5: How do I know which series I need?
A: Start with your required output torque and shaft orientation. If your torque exceeds the F series rating for your frame and ratio, move to ZY or H/B. Choose ZY for cost-effective parallel shaft solutions within its rated range. Choose H series (H2/H3/H4) for parallel shaft above ZY range. Choose B series (B2/B3/B4) for right-angle up to 290 kN·m. Right-angle above 290 kN·m is not available in B series.

📩 Contact our technical team for ZY/H/B series sizing, torque verification, and configuration selection for your crusher application

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✦ HelmeDrive.com - Professional manufacturer of industrial gearbox in China ✦

^✦ Gear Motor | Gear Unit | Industrial Gearbox ^✦

🌐 Contact us for a comparison quote:

📩  shawn.zhu@helmedrive.com  

📞 WhatsApp:  [+86-13196785788]