As a general guide, the Mini suits compact excavators and smaller posts, the Midi provides greater capacity for general fencing work, and the Maxi is intended for larger posts and heavier applications.
Excavator weight should not be considered on its own. The machine must also provide the hydraulic flow required by the Postmaster.
Mini Postmaster
The Mini Postmaster is designed for compact excavators from 1.5 to 3 tonnes and posts up to 150mm (6") diameter.
It produces 50 kN of eccentric force and requires a double-acting hydraulic service delivering 30–40 l/min, with a maximum pressure of 200 bar.
Its compact carrier requirements make the Mini particularly useful for smaller fencing jobs and locations where access or manoeuvrability limits the size of machine that can be used.
Mini Postmaster Specifications
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Eccentric force: 50 kN
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Maximum post diameter: 150mm / 6"
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Excavator size: 1.5–3 tonnes
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Hydraulic flow: 30–40 l/min
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Hydraulic service: Double acting
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Maximum pressure: 200 bar
Midi Postmaster
The Midi Postmaster is the middle model in the range and is designed for 2.5 to 5 tonne excavators.
With 60 kN of eccentric force, it accommodates posts up to 200mm (8") diameter and requires 35–46 l/min from a double-acting hydraulic service.
This additional capacity makes the Midi suitable for general fencing work where larger posts are required without moving up to the carrier and hydraulic requirements of the Maxi.
Midi Postmaster Specifications
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Eccentric force: 60 kN
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Maximum post diameter: 200mm / 8"
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Excavator size: 2.5–5 tonnes
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Hydraulic flow: 35–46 l/min
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Hydraulic service: Double acting
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Maximum pressure: 200 bar
Maxi Postmaster
For larger post-driving applications, the Maxi Postmaster is designed for excavators between 5 and 8 tonnes.
It delivers 110 kN of eccentric force and accommodates posts up to 300mm (12") diameter.
The Maxi requires a double-acting hydraulic service delivering 60–80 l/min, with a maximum pressure of 200 bar.
Maxi Postmaster Specifications
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Eccentric force: 110 kN
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Maximum post diameter: 300mm / 12"
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Excavator size: 5–8 tonnes
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Hydraulic flow: 60–80 l/min
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Hydraulic service: Double acting
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Maximum pressure: 200 bar
What Carrier Does the Postmaster Mount On?
The standard Postmaster range is designed around excavators, with the Mini, Midi and Maxi covering machines from 1.5 to 8 tonnes.
However, other mounting arrangements are possible.
We list a loader mounting bracket as optional equipment, allowing the Postmaster to hang correctly when fitted to a loader.
Custom engineering and mounting solutions may also be possible for particular applications.
Before ordering, check:
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Carrier make and model
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Operating weight
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Auxiliary hydraulic flow
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Maximum hydraulic pressure
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Double-acting hydraulic service
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Attachment arrangement
Providing this information when enquiring makes it easier for us to identify the appropriate Postmaster and mounting configuration for your project.
Hydraulic Requirements
Matching the Postmaster to the carrier's hydraulic system is essential.
A machine may fall within the recommended excavator weight range but still be unsuitable if it cannot provide the required hydraulic flow.
Conversely, some jobs require a larger carrier for additional reach or access.
Where that carrier supplies more oil than the Postmaster requires, we offer a flow divider to regulate the supply and protect the hydraulic motor and seals.
Always check your carrier's hydraulic specification rather than choosing solely by machine weight.
What Size and Type of Posts Can the Postmaster Handle?
The maximum diameter increases through the range from 150mm with the Mini to 300mm with the Maxi.
Post shape also matters.
The Postmaster jaw system can accommodate different post profiles.
The current Maxi manual, for example, provides jaw positions for round posts between 3 and 12 inches and square posts up to 8 inches.
At Autoguide, we can also manufacture custom jaws for specialist applications where a standard configuration is unsuitable, making it important to provide the post dimensions and profile when requesting a recommendation, particularly when working with non-standard posts.
Which Postmaster Is Suitable for Different Ground Conditions?
There is no single model that should be selected solely because ground is harder.
Carrier capacity, post dimensions and hydraulic requirements still need to be considered together.
Where conditions allow, the Postmaster can drive the post directly into the ground.
For more difficult conditions, we offer a rock spike that creates a pilot before the post is installed.
The standard spike is 60mm in diameter and 1 metre long and can be held by the standard jaws.
A dibber is also available where the installation requires a prepared void for concrete backfilling.
Very difficult ground, substantial rock or buried obstructions may require another installation method. In these situations, drilling before installing the post may be more appropriate.
Read our guide to choosing an auger by machine, ground and job for more information about matching drilling equipment to the carrier and ground conditions.
Postmaster or Auger?
The main difference is straightforward:
A Postmaster drives the post into suitable ground, whereas an auger drills a hole before the post is installed.
Driving can remove the separate stages of excavating and backfilling individual holes where the post and ground conditions permit it.
An auger may be more appropriate when a prepared hole is required, when the installation needs concrete backfilling or when the ground cannot accept a directly driven post.
The choice should therefore be based on your installation specification and site conditions rather than treating one method as universally better than the other.
Installing, Removing and Repositioning Posts
Post installation is only one function of the Postmaster.
Its hydraulic clamp can grip an existing post so that it can be extracted or repositioned. This is useful when replacing damaged fencing, altering an existing fence line or correcting the position of a post.
The clamping system also holds the post securely during installation, helping to minimise damage to its top.
Should I Hire or Buy a Postmaster?
Both options can make sense depending on how frequently the equipment will be used.
When Hiring May Make Sense
Consider Postmaster hire if the equipment is required for:
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A one-off fencing contract
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Short-term work
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Seasonal projects
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Occasional post installation
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Testing the equipment before purchasing
When Buying May Make Sense
Purchasing a Postmaster may be more appropriate when post installation is a regular part of the business.
That can include fencing contractors, agricultural contractors, farms and estates, groundworkers and plant hire businesses.
Instead of comparing the purchase price with a single hire charge, consider expected annual utilisation, repeated hire costs, equipment availability during busy periods and whether you already own a suitable carrier.
Contact Autoguide Equipment for current purchase information and Postmaster hire availability.
Looking for a Post Knocker for Sale?
If you are looking for a post knocker for sale, matching the attachment correctly to your existing equipment is more important than simply choosing the largest model.
Before enquiring about a Postmaster, have the following information available:
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Carrier make and model
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Machine operating weight
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Hydraulic flow
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Hydraulic pressure
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Maximum post diameter
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Post shape
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Typical ground conditions
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Expected frequency of use
At Autoguide, we can use these details to determine whether the Mini, Midi or Maxi is appropriate and identify any additional mounting or ground-preparation equipment required.
For current pricing and availability, contact us today on +44 (0)1380 850885.
Optional Equipment for the Postmaster
Additional equipment can adapt the Postmaster to particular machines, posts and site conditions.
Flow Divider: Regulates hydraulic flow when a larger carrier supplies more oil than the Postmaster requires.
Loader Mounting Bracket: Provides an alternative mounting arrangement for loader applications.
Rock Spike: Creates a pilot for a post in more difficult ground. The standard spike measures 60mm × 1m.
Dibber: Creates a compacted void ready for concrete backfilling.
Custom jaws and other engineered solutions may also be available where standard equipment does not suit the post or application.
Postmaster Manuals and Technical Information
Autoguide provides separate operating manuals and parts information for the Mini/Midi and Maxi Postmasters.
These contain important information about operation, hydraulic requirements, jaw adjustment and parts.
View our postmaster manuals if you need technical information for a particular machine.
Find the Right Postmaster
Choosing between the Mini, Midi and Maxi starts with the machine you already operate and the posts you need to install.
Send us your carrier details, hydraulic flow, post dimensions and expected ground conditions and the team can advise on the appropriate model and mounting arrangement.
Postmasters are available for both purchase and hire.
Contact us to discuss your project requirements.
Frequently Asked Questions About Postmaster Post Drivers
1. What is the Autoguide Postmaster?
The Autoguide Postmaster is a hydraulic vibrating post driver used to install, extract and reposition posts. It mounts to a suitable excavator or compatible hydraulic carrier and uses a clamping system to hold the post during operation.
2. Is a Postmaster the same as a post knocker?
Post knocker is a common term for machinery used to drive posts into the ground. The Postmaster performs this job using hydraulic vibration and may therefore be described as a hydraulic post knocker or post driver.
3. Which Postmaster do I need?
Choose the model according to your carrier, hydraulic output and post dimensions. The Mini is designed for 1.5–3 tonne excavators, the Midi for 2.5–5 tonnes and the Maxi for 5–8 tonnes. Ground conditions should also be considered before installation.
4. What is the largest post a Postmaster can handle?
The Mini accommodates posts up to 150mm (6") diameter, the Midi up to 200mm (8") and the Maxi up to 300mm (12").
5. What hydraulic flow does a Postmaster require?
The Mini requires 30–40 l/min, the Midi 35–46 l/min and the Maxi 60–80 l/min. All three require a double-acting hydraulic service and have a maximum pressure specification of 200 bar.
6. Can a Postmaster be mounted on a loader?
At Autoguide, we list a loader mounting bracket as optional equipment for the Postmaster. Carrier suitability and hydraulic requirements should be confirmed before specifying an alternative mounting arrangement.
7. Can a Postmaster work in hard or rocky ground?
A rock spike can be used to create a pilot in more difficult ground before installing the post. Conditions vary, however, and substantial rock or obstructions may require drilling or another installation method.
8. Can the Postmaster remove existing posts?
Yes. Its hydraulic jaws can grip posts for extraction as well as installation, making it useful for replacing damaged posts, removing old fencing and repositioning posts.
9. Is it better to hire or buy a Postmaster?
Hire can suit one-off or occasional projects, while purchasing may be more appropriate when post installation is a regular part of your work. The decision should consider annual usage, repeated hire costs, availability and whether you already have a compatible carrier.
10. Where can I buy a Postmaster post driver?
Postmasters can be purchased directly from Autoguide Equipment. Provide our team with your carrier specifications, hydraulic flow, post dimensions and typical ground conditions so we can advise you on the appropriate model.
11. Can I hire a Postmaster?
Yes. We offer Mini, Midi and Maxi Postmasters for hire. Email us with your enquiry to check the appropriate model and current availability.
12. Where can I find Postmaster technical information?
Operating manuals and parts information for the Mini, Midi and Maxi are available through our Postmaster Manuals.
