How Bucket Geometry Affects Material Throw: Deep (DS) vs. Shallow (DQ) Designs

Introducción

In industrial bulk material conveying — grain handling, feed manufacturing, chemical processing — the elevator cup is not simply a container that carries material upward. Its geometry directly determines how material is loaded at the boot, how completely it is discharged at the head, and whether backflow occurs on the return run. Get the geometry wrong, and even a correctly specified chain, sprocket, and drive system will produce suboptimal throughput, incomplete discharge, and material losses.

Specifically, the choice between DS (deep) and DQ (shallow) elevator cup profiles is the most fundamental geometry decision in industrial elevator specification. Both are defined by the same five dimensional parameters — A, B, C, D, and E — but their proportional relationships differ in ways that produce significantly different material handling behaviour at the same chain speed.

This article explains the A/B/C/D/E measurement system, how each dimension affects material behaviour, and the engineering logic that determines when DS deep cups outperform DQ shallow cups, and vice versa.

For complete DS and DQ size charts and ordering: DS & DQ Industrial Elevator Cups product page.

Section 1 — The A/B/C/D/E System

The Five Dimensions That Define Elevator Cup Performance

Every DS and DQ elevator cup is fully described by five dimensional parameters. Understanding each parameter — and specifically how it affects material behaviour — is the basis for correct cup selection and replacement specification.

The C/B Ratio: The Key Differentiator Between DS and DQ

The ratio of inner cavity depth (C) to projection depth (B) is the defining geometric difference between DS deep and DQ shallow elevator cups. For DS cups, C is typically 85–95% of B — the cavity is almost as deep as the cup projects from the back plate, producing a deep, bucket-like profile. For DQ cups, C is typically 60–75% of B — the cavity is shallower relative to the projection, producing a wide, scoop-like profile.

This ratio directly affects discharge behaviour. At a given centrifugal speed (determined by chain speed and sprocket radius), a DS cup holds material securely in its deep cavity throughout the vertical lift and releases it cleanly at the discharge point. A DQ cup, by contrast, begins to release material earlier in the discharge arc — a feature that is advantageous for inclined elevators but causes premature discharge (and backflow) on steep vertical elevators.

Section 2 — Fill Rate and Discharge Throw

How Geometry Affects Fill Rate, Discharge Throw, and Throughput

Fill Rate: A and B Working Together

The fill rate of an elevator cup — the proportion of the cup’s theoretical volume that is actually filled on each pass through the boot — is determined by the interaction of the A dimension (fill width) and B dimension (projection depth). A wider, deeper cup will intercept more material per cycle. However, the relationship is not simply linear: cups that are too wide relative to the boot geometry create interference between adjacent cups, reducing fill efficiency.

In practice, fill rates for DS and DQ cups in well-designed elevator boots typically range from 65% to 85% of theoretical capacity. Therefore, when calculating throughput, always use 70% of theoretical as a conservative starting point and verify against actual throughput after installation.

Discharge Throw: Why Elevator Angle Determines Cup Profile

At the discharge point, material exits the cup through centrifugal force as the cup travels around the head sprocket. The centrifugal force is proportional to the cup speed and the radius at which the material sits in the cup. For a DS deep cup, material sits further from the sprocket centre (because the cavity is deep), generating higher centrifugal force and a longer discharge throw. This longer throw is necessary for clean, complete discharge on a vertical elevator where the discharge chute is positioned away from the sprocket.

For a DQ shallow cup on an inclined elevator, however, the shorter throw from the shallow cavity geometry aligns better with the shorter distance to the discharge chute. Consequently, DQ cups produce cleaner discharge on inclined elevators than DS cups at the same chain speed — and DS cups produce cleaner discharge on vertical elevators than DQ cups.

The critical error to avoid: Fitting DS deep cups on a steeply inclined elevator produces incomplete fill at the boot (the deep cavity creates turbulence in the material stream at high inclination angles) and over-throw at discharge (the longer centrifugal throw overshoots the discharge chute). Fitting DQ shallow cups on a vertical elevator produces under-throw at discharge — material falls short of the discharge chute, creating backflow and spillage. Match the cup profile to the elevator angle.

Section 3 — Selecting by Application

DS vs DQ: Matching Cup Profile to Elevator Design

Conclusión

Geometry Is Performance: Specify the Profile Before the Size

The DS and DQ elevator cup selection decision should be made before the size decision. Profile determines whether the cup fills efficiently at the boot and discharges cleanly at the head — and a correctly sized cup with the wrong profile will underperform regardless of its capacity. Once the profile is confirmed (DS for vertical, DQ for inclined), size selection follows from the throughput calculation using the A/B/C/D/E dimensions.

Need help selecting DS or DQ for your elevator? Send us your elevator inclination angle, chain speed, and product type. We recommend the correct profile and size within 24 hours. Contact our technical team →

Continúa leyendo: DS vs. DQ Series: Optimizing Backflow Prevention in High-Speed Elevators →