SPA BTL V-pulleys

Hangzhou Ocean Industry Co., Ltd. is one of the leading manufacturers and suppliers of spa btl v-pulleys in China. Welcome to wholesale bulk durable industrial chains and power transmission parts made in China here from our factory. All customized products are with high quality and competitive price.

 

 

We produce the whole SPA range of taper bore V-pulleys, and the range runs from a 63 mm pitch diameter single groove pulley to a six groove 1000 mm one. Every pulley in it is cast in GG25 iron, machined to the DIN dimensions, finished to a fine surface in the groove and assembled on a taper bush.

What makes the range useful. The bush does the fitting, so a pulley can be put on a shaft and taken off again with hand tools. One pulley body covers a wide spread of shaft sizes because the bush is exchangeable, and the grooves are made in six configurations so a given diameter can carry anything from one belt to six.

How they are built. Cast in GG25 grey iron, machined to the DIN dimensions, balanced where the size requires it, and finished with the groove left as cut.

What this page covers. The product range in one table, the six series with their drawings and dimension tables, how to read those tables, the advantages of the range, how the pulleys are produced, the quality checks they pass through, the production capacity behind them, and the ordering information.

SPA is the narrowest of the four classical wedge belt sections, and a taper bore SPA pulley is one that mounts on a tapered bush instead of on a bored hub. The two things are independent: SPA describes the groove, the taper describes the mounting, and this range supplies both.

Separating the two is what makes the range practical. A bored pulley commits the purchaser to a shaft diameter at the moment of ordering, and taking it off again normally needs a puller. With a taper bush the pulley is held by the bush, so it suits any shaft the bush suits and is released with the same screws that fitted it.

That is why the range is stocked in the form it is. A distributor can hold pulley bodies and a set of bushes and cover a much wider combination of ratio and shaft size than the same money spent on bored pulleys would allow, and a plant repairing a drive can fit what is on the shelf rather than waiting for a bored pulley to be made.

 

The table sets the range out in one view: the standard the pulleys are made to, the six series, and the diameters each series covers. All six are DIN dimensioned.

Standards	Series Type	Size Range
DIN	SPA-1	SPA63-01 to SPA630-01
	SPA-2	SPA63-02 to SPA630-02
	SPA-3	SPA71-03 to SPA1000-03
	SPA-4	SPA90-04 to SPA1000-04
	SPA-5	SPA100-05 to SPA1000-05
	SPA-6	SPA100-06 to SPA1000-06

 

The series number is the groove count, and it is the first thing to establish. SPA-1 is a single groove pulley, SPA-2 a double groove, and the series runs to SPA-6 for a six groove pulley. The number is not a size; it is how many belts the pulley carries.

The size range in each row is written as a span between two pitch diameters. SPA-1 covers SPA63-01 to SPA630-01, meaning a 63 mm pitch diameter single groove pulley up to a 630 mm one. SPA-3 and above start at larger diameters and carry on further, because a pulley cannot be made with three or four grooves in the smallest sizes: there is not enough material between the bore and the first groove.

That is why the ranges begin at different points. SPA-1 starts at 63 mm, SPA-3 at 71 mm, SPA-4 at 90 mm and SPA-5 and SPA-6 at 100 mm, while the top of the range extends to 1000 mm for the three, four, five and six groove types. A duty that needs both a small diameter and several grooves is a duty that does not exist.

When a duty sits between two catalogue sizes, the bush columns are as important as the diameters, because a pulley with a suitable pitch diameter but a bush too small for the shaft cannot be used on that drive.

 

The six tables use the same set of headings, and because they are what a drive is designed around, they are worth working through once.

P.D is the pitch diameter; O.D is the outside diameter. A ratio or a speed calculation uses the first, while the second is what has to clear the guard. The Type entry records the bush and groove form the pulley is built around.

Type describes which bush and which groove form the pulley is built around; two pulleys with the same diameters can be different types and take different bushes. Bush No. is the taper bush the pulley is machined for, and Max Bore is the largest shaft that bush will take.

The lettered columns describe the hub and the belt line. E, F, J and K locate the grooves and the hub relative to the bush and to the shaft end, which is what decides where the belts sit once the pulley is fitted. L and M are the hub and overall dimensions, and N is the dimension across the largest part of the pulley. Where a dash appears, the dimension does not apply to that size.

 

Six advantages matter on this range, and they are the reasons it is specified rather than a bored pulley.

The bush makes the fitting reversible. The pulley is clamped on by drawing the bush into it, and it is released with the same screws turned into the release holes. There is no puller, no heat and no risk of scoring a shaft, which matters on a motor shaft that would be expensive to replace.

One pulley covers many shafts. Because the bore is in the bush and not in the pulley, the same pulley body suits any shaft diameter the bush is made in. A plant holds a set of bushes and covers far more of its drive population than the same shelf space of bored pulleys would cover.

Assembly is precise and repeatable. The taper centres the pulley on the bush as it is tightened, so concentricity comes from the fit rather than from the operator's judgement, and a pulley refitted after maintenance goes back in the same position.

The range is complete. Six groove configurations from 63 mm to 1000 mm pitch diameter on DIN dimensions means a drive can be designed within one system rather than assembled from several suppliers' parts, and a machine can be re-rated later without changing the pulley system.

GG25 with a properly finished groove. Grey iron takes the fine cut a wedge belt groove needs, damps the drive rather than ringing under it, and wears in a way that a service measurement can follow.

Matched with BTL bushes. Every series on this page can be supplied with BTL bushes, so the pulley and its mounting come from one specification and one dimensional system rather than from two.

 

How the line is arranged. Production runs as a sequence of stages rather than as separate workshops, and each stage is set up around the size being cast rather than around a single product.

Casting. The pulley bodies are cast in GG25 grey iron from patterns held for each diameter and groove configuration. The casting is made with enough stock on the surfaces that will be machined, and with the hub formed in the same pour as the rim, so the two are one piece of metal rather than an assembly.

Fettling and preparation. The casting is cleaned, the runners are removed and the surfaces that will be machined are dressed. This stage decides a lot of what follows: a casting that has not been prepared properly will not sit consistently in the fixtures, and a pulley that does not sit consistently cannot be machined to a consistent pitch diameter.

Machining. The bore and the taper seat are machined first, because the groove dimensions are referenced to them. The groove or grooves are then cut to the section profile, and the outside diameter and the face dimensions are turned. Because the pitch diameter is generated by the groove depth rather than by the outside diameter, the groove tool and its setting are what hold the ratio of the pulley, and they are checked rather than assumed.

Balancing and finishing. Rotationally, a pulley is an unbalanced mass by nature, and larger diameters are balanced after machining. The finish is then applied to the outside while the groove is left as machined, because a belt has to run on metal rather than on paint.

Assembly and packing. The pulley is checked against the bush it will be supplied with, and the two are packed together where they are ordered as a set. Each pulley is boxed individually, which protects the groove in transit.

 

What is checked, and when. Quality control on a pulley follows the order of the process, because a defect found at the end of the line is an expensive way to find it.

Incoming material. The iron is confirmed against the grade the castings are made to, so that the pulley that is machined has the material the drawing assumes.

At the casting. Castings are checked for the dimensions that have to be right before machining, and for the defects that machining cannot recover: blowholes in a machined surface, a short pour at the rim, or a distorted hub.

After machining. Pitch diameter and groove profile are measured, since these two set the ratio and the belt fit. Concentricity between the taper seat and the grooves is checked, because a pulley that is out of round on its bush runs out on the shaft. The bush seat is gauged to the bush that will be fitted to it, not to a nominal size.

Before packing. The assembled pulley and bush are checked as a pair, and the dimensions that position the belt line are confirmed against the table before the pulley is boxed. This is the check that catches the errors which would otherwise only appear when the pulley is on the machine.

Records. The paperwork is filed by order number, so a pulley working in the field can be traced back to the casting and the machining run it came from. If the paperwork has to accompany the shipment, raise it when the order is placed.

 

What the capacity is measured in. For a cast and machined product, capacity is not one number. It is the range of sizes that can be cast, the range that can be machined with the tooling on hand, and how much of the range is held as stock rather than made to order.

Range capability. The line covers SPA pulleys from 63 mm to 1000 mm pitch diameter across six groove configurations, with bush sizes from 1008 up to 4545 and bores up to 110 mm, so a drive can be re-rated without leaving the system.

Shelf stock and made-to-order. The sizes in common use are kept and can be dispatched quickly, which is what a breakdown calls for. Sizes outside that range are cast and machined against the order.

What drives the lead time. Two things move a delivery date more than anything else: whether the size is stocked, and whether the pulley needs a bush that is not held. Ordering the pulley and its bush together is therefore quicker as well as safer, because it avoids two schedules having to meet.

Where a capacity figure is needed. For a project that requires quantities or a schedule confirmed in writing, tell us the sizes and the annual volume and we will quote against them. We would rather commit to a date we have checked than publish a generic figure that does not hold for the sizes you actually need.

GG25 Iron and the BTL Bush System

['GG25 grey cast iron. GG25 is a flake graphite grey iron, and it is the traditional material for a V-pulley of this size because it does several jobs at once: it machines to a fine surface in the groove, it damps vibration instead of ringing, and it wears in a progressive way that can be measured.', "Why the groove matters more than the outside. A wedge belt does not sit on the bottom of the groove; it contacts the two flanks. That means the groove angle, the depth and the surface finish decide how much of the belt's capacity is usable, and a groove that is worn or wrongly cut will slip a belt that the outside diameter suggests should be adequate.", 'The BTL bush. A taper bush is a split sleeve with a tapered outside and a parallel bore. Drawing it into the pulley closes the taper, which clamps the bush onto the shaft and the pulley onto the bush in the same movement. Reversing the screws pushes the two apart again. The system is used across the range because it makes the pulley removable without damaging the shaft.', 'How pulley and bush are specified together. The pulley tables give the bush number and the maximum bore for each size, which is the linking information between a pulley and a shaft. Read those two columns before anything else, because they decide whether the pulley can be fitted at all.']

 

GG25 grey cast iron. GG25 is a flake graphite grey iron, and it is the traditional material for a V-pulley of this size because it does several jobs at once: it machines to a fine surface in the groove, it damps vibration instead of ringing, and it wears in a progressive way that can be measured.

Why the groove matters more than the outside. A wedge belt does not sit on the bottom of the groove; it contacts the two flanks. That means the groove angle, the depth and the surface finish decide how much of the belt capacity is usable, and a groove that is worn or wrongly cut will slip a belt that the outside diameter suggests should be adequate.

The BTL bush. A taper bush is a split sleeve with a tapered outside and a parallel bore. Drawing it into the pulley closes the taper, which clamps the bush onto the shaft and the pulley onto the bush in the same movement. Turning the screws into the release holes pushes the two apart again.

How pulley and bush are specified together. The pulley tables give the bush number and the maximum bore for every size, which is the linking information between a pulley and a shaft. Read those two columns before anything else, because they decide whether the pulley can be fitted at all.

 

Begin by cleaning the two tapered surfaces, the outside of the bush and the bore in the pulley, and running a finger over both for burrs. Anything trapped between them holds the assembly off its seat, and no amount of care further along the drive will correct a pulley that is not sitting squarely.

Bush first, then the pulley. The bush is placed on the shaft with its key in position, the pulley is slid onto the bush, and the screws are started by hand before being taken up evenly.

Coplanarity is checked before the belts go on. With the pulley fitted, the two pulleys of the drive are lined up with a straight edge laid across their faces. Doing it at this stage costs a few minutes; discovering the same misalignment later usually means replacing a belt that has worn along one edge.

Check again after the first run. Tension is set to the published figure for the section in use and looked at again after a few hours, because a new belt beds into its groove. The mounting screws are worth checking on the same visit.

 

The four sections are a series rather than four alternatives, and the difference between them is belt width and therefore how much power one groove will carry.

SPZ is the narrowest and carries the least in a single groove, which makes it the section for small diameters and high speeds. SPA is the next section up and the one this page covers, with a groove form that suits the range from 63 mm upward. SPB is wider again, for drives that need more capacity per groove, and SPC is the widest of the four, used at the largest diameters and the heaviest duties.

The practical consequence is that the same pulley diameter in two sections is not the same pulley. A groove is cut for one section profile, so an SPA pulley will not correctly run an SPB belt and the two cannot be interchanged by adjusting the drive.

Where the decision is made. Establish the section before the diameter. The section is normally fixed by the machine or the duty, and once it is known the pitch diameter follows from the ratio and the speed, and the pulley is then selected from the table for that series.

This page covers SPA in full. SPB, SPC and SPZ are catalogued separately on their own pages, and the same selection method applies to each.

 

In-house from casting to finish. Casting, machining and finishing run as one sequence rather than being bought in as finished parts, which is what lets a pulley ordered today match one supplied years ago.

On a drive that may stay in service for decades, the value of a fixed range is that a replacement sits where the original did. Any deviation shows up as a belt running out of line with the pulleys around it, which is easier to prevent than to diagnose.

Export record. The company has been exporting since 2005, with Europe as the largest market, and pulleys have gone out to North America and Southeast Asia alongside it.

Language. Correspondence, drawings and inspection documents are handled in English.

 

Q: What is an SPA taper bore V-pulley?
A: A V-pulley with an SPA section groove that mounts on a tapered bush instead of on a bored hub. The bush clamps the pulley to the shaft, so the pulley can be fitted and removed with hand tools and suits any shaft diameter the bush is made in.

Q: What is the difference between SPA-1 and SPA-6?
A: The number is the groove count, not a size. SPA-1 is a single groove pulley, SPA-6 carries six belts, and the range between them covers two, three, four and five groove configurations.

Q: Which diameters does the range cover?
A: From 63 mm to 630 mm pitch diameter on the single groove series, and up to 1000 mm on the three, four, five and six groove series. Each series starts where there is enough material in the hub to cut the grooves it carries.

Q: Is the pitch diameter the same as the outside diameter?
A: No. The pitch diameter is the diameter the belt runs on and is the figure a ratio is calculated from. The outside diameter is larger and is the figure that decides what the pulley will clear.

Q: What bush sizes are used?
A: The tables give the bush number for every size, running from 1008 on the smallest pulleys up to 4545 on the largest, with maximum bores from 28 mm to 110 mm depending on the size.

Q: What does the pulley weigh, and can one person fit it?
A: Weight rises steeply with diameter, and on the larger sizes the pulley is a two-person lift or a crane job. The tables give the dimensions; if you need the mass of a particular size for a handling plan, ask and we will confirm it for that part number.

Q: What material are they made from?
A: GG25 grey cast iron. It machines to the fine surface a wedge belt groove needs, damps vibration, and wears progressively so that groove wear can be measured at a service.

Q: Can they be supplied with BTL bushes?
A: Yes. Every series on this page can be matched with BTL bushes, so the pulley and its mounting come from one specification.

Q: How do I know which series to order?
A: Establish the belt section first, then the ratio and the speed, which give the pitch diameter, then the number of belts the duty needs, which gives the series. Finally check the bush number against the shaft diameter.

Q: Can a pulley be re-used with a different shaft size?
A: Yes, and that is one of the main advantages of the range. The bore is in the bush, so changing the bush changes the shaft size without changing the pulley.

Q: Is there a tightening sequence for the mounting screws?
A: Yes. Bring them up by hand first, then take them up progressively in turn rather than finishing one screw before starting the next, because the taper is closed evenly by all of them together. The torque figure for the bush size comes from the bush manufacturer's data.

Q: Does the range have to be balanced?
A: Larger diameters are balanced after machining, because a pulley is an unbalanced mass by nature and the effect grows with diameter and speed. If a specific balancing grade is required for a high speed drive, state it when ordering.

Q: Which sizes are held in stock?
A: Common sizes are held for prompt delivery, and sizes outside the stocked range are cast and machined to order. Asking which category a particular size falls into is the quickest way to get a realistic delivery date.

Q: Is SPA interchangeable with SPB, SPC or SPZ?
A: No. Each section has its own groove profile, so a belt of one section will not run correctly in a pulley cut for another. The section has to be established before the pulley is selected.

 

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