Curtainsider trailers are often purchased based on whole-life performance and value: durability, ease of loading/unloading, impact resistance, minimal downtime, low maintenance and designed to optimise payload fill.
With this in mind, Don-Bur design and manufacture the complete range of curtainsider trailers developed and engineered around each operation rather than a fixed template. As a result, we deliver innovative and long-lasting products that have driven unrivalled customer loyalty.
Engineering durable curtainsider trailers for intensive use
In order to design the best solutions, we work closely with customers to understand the operation including depot layout, bay design, materials handling, payload weight/type and load restraint requirements.
Working continually with our customer base over decades has driven ongoing product design evolution, introducing improvements that increase loading efficiency, reduce fuel consumption, minimise operational damage and adapt to changing compliance requirements.
Specification approach
Curtainsiders are engineered around the operation rather than a fixed template. Core decisions typically include:
- Dimensions and cube: overall height, aperture height and length to suit route restrictions and required payload volume.
- Mass and running gear: axle number, wheelbase, suspension and brake specification to balance tare weight, durability and manoeuvrability.
- Chassis and structure: straight-frame or step-frame layouts with heavy-duty construction matched to utilisation and loading frequency.
- Access and closure: pillarless side access and rear door or shutter arrangements suited to depot handling methods.
- Floor and load containment: floor strength, EN 12642-XL body performance and the restraint method appropriate for the freight.
The objective is consistent: a durable trailer that loads efficiently, protects the freight and delivers predictable whole-life operating cost.
All curtainsiders are built to EN 12642-XL as standard and can be configured across a wide dimensional and running-gear range to suit the duty cycle.
To ensure peace of mind, we provide a comprehensive warranty and after sales support package.
"driving innovation | delivering value"
EN 12642-XL
EN 12642-XL is the recognised European standard for whole-body load containment. For curtain-sided bodywork, it defines minimum structural resistance and acceptable deformation under forward, rearward and lateral loading. These tests verify that the body contributes to stabilising correctly positioned freight during normal road transport.
All Don-Bur curtainsiders are built to EN 12642-XL as standard, providing a documented and independently verified level of structural performance without needing to specify the rating as an optional extra.
XL rating does not remove the need for appropriate load restraint, but it provides a proven containment baseline. In the UK, the DVSA accepts EN 12642-XL as supporting evidence of adequate load containment when freight is positioned to achieve positive fit, reducing reliance on additional lashings for many palletised goods.
Load restraint options
Safe transport depends on selecting restraint equipment suited to the freight, vehicle type and operating environment. Curtainsiders rely on suitable restraint systems to minimise movement during normal driving conditions.
- EN 12195-2 compliant rave-to-rave webbing straps: widely used for stabilising palletised goods across the full trailer width.
- Roof-mounted straps: suitable for loads up to 400 kg.
- Transverse nets (kites): useful for limiting forward or rearward movement of mixed or lighter palletised loads.
- Side nets: assist with controlling lateral movement of irregular freight or part loads.
- EN 12640 lashing points: factory-tested anchorage points for attaching straps or chains where item-specific restraint is required.
These systems complement XL-rated bodywork but do not replace correct load positioning. Loads should be arranged to achieve positive fit wherever possible and restrained according to the type of freight and expected route conditions.
Durability, after-sales and warranty support
Long-term service life is a core design consideration. Don-Bur chassis units use a heavy-duty all-bolted construction and are commonly specified with localised galvanisation to protect against road spray, salt and weathering. Reinforced cant-rails, robust crossbearers and high-wear components are selected to withstand repeated forklift side loading and high utilisation across varied routes.
Where the operation demands it, specifications can be engineered around known failure points in intensive use. Options such as stainless-steel hardware, reinforced wear bands and higher-grade curtain fabrics can be selected to reduce maintenance frequency and extend service life in high-wear environments.
Operators commonly evaluate durability alongside the quality of after-sales and warranty backup. Support requirements vary by fleet maintenance model, duty cycle and route exposure, so specification and documentation are aligned to how the trailer will be inspected, maintained and repaired over its working life.
Heavy duty flooring options
Floor specification is matched to duty cycle and loading method, with a focus on forklift loading, abrasion and impact exposure. Heavy duty options include phenolic-coated plywood and hardwood planking. Reinforcement can be added where concentrated forklift axle loads are expected.
Additional anti-slip surfaces, rear steel "dump" plates and local strengthening are fitted where required to protect high-wear zones and reduce damage from frequent loading and unloading.
Rear closure options
Rear access can be configured with container doors, flush-fit barn doors, roller shutters or simple fixed panels. Enhanced sealing and optional TIR capability can be integrated for routes requiring added security or cross-border conformity.
Branding and Livery
Don-Bur has its own in-house "Sapphire" graphics division providing full branding and livery options including printed curtains, vinyl graphics and operational decals.
These support fleet identity, marketing messages and operational compliance.
Curtainsider Trailer specification matrix
The following overview summarises some of the main specification areas available on Don-Bur curtainsider trailers and the engineering factors that typically determine each selection. All trailers are designed to individual operator requirements.
Further options are available.
| Typical Options | Engineering Notes | |
|---|---|---|
| Body Height / Aperture Height | Typical overall heights range from: • ~3.60 m (urban delivery) • 4.00 m (European maximum) • 4.20 m (common UK height) • 4.50 m ("tall boy" high-volume builds) • Up to ~4.95 m (maximum) Side and rear aperture heights vary accordingly. |
As a rule of thumb, apertures on straight-frame chassis are calculated as: aperture height ≈ overall height − 1550 mm. For example, a 4.00 m trailer typically achieves a side aperture of approximately 2450 mm. Slimline "mega" neck designs and slimline cant-rails can increase aperture height further by reducing structural depth without compromising strength. |
| Length | Length is fully configurable and depends on route type and operational geometry. Typical ranges include: • 13.7 m (standard UK semi-trailer) • Up to 15.650 m for LST-compliant designs • Reduced lengths from ~8 m for urban, tight-access or multi-drop operations |
Length is determined by the operating environment, turning-circle requirements, tractor compatibility and desired internal volume. Shorter bodies improve manoeuvrability in congested or restricted sites, while LST configurations maximise payload and cube on trunking routes where regulations allow their use. |
| Wheelbase (Kingpin → Axle Centreline) | • Up to ~8.100 m on standard 13.7 m trailers • Shorter wheelbases for reduced-length or urban builds • LST configurations typically incorporate a steer axle |
A wheelbase of up to ~8.135 m meets the UK "deemed to comply" turning-circle rule for conventional 13.7 m tri-axle semi-trailers. Shorter trailer bodies use reduced wheelbases to maintain manoeuvrability and axle-load balance. LST designs require more complex arrangements and generally rely on steer axles to achieve mandated turning-performance requirements. |
| Axle Type | BPW, SAF or JOST; drum or disc brakes; optional lift/steer | Based on fleet standardisation, maintenance planning and route-specific handling or weight-transfer needs. |
| Wheel Size | Wheel and tyre combinations typically include: • 17.5" twins (small diameter) • 19.5" twins or mini-singles • 22.5" super-singles (e.g. 385/65 R22.5) |
Tyre diameter has a direct impact on rear bearer height and therefore achievable internal cube. Smaller 17.5" twin wheelsets can result in bearer heights of ~880 mm, maximising internal height. Typical 385/65 R22.5 super-singles produce bearer heights around ~1250 mm, balancing cube, stability and durability. Selection depends on load type, desired internal height, running-cost considerations and fleet standardisation. |
| Braking System | Haldex, Knorr-Bremse or Wabco (ZF); optional EBPMS | Configured to operator preference, compliance requirements and integration with fleet telematics or maintenance reporting. |
| Coupling Box Type | Fixed coupling box, sliding coupling, double sliding rail, LowGlide safe ground coupling | Driven by tractor variations, coupling frequency and required safety standards. |
| Rear Closure Type | Container-style doors (single or double locking bars), wide-lath roller shutters, fixed panel | Selected based on access method, required security level, load type and depot handling equipment. |
| Internal Load Restraint | Rave straps, roof-mounted straps, nets, side nets, EN 12640 lashing points | Chosen according to freight stability, load positioning, multi-drop patterns and regulatory expectations. |
| Floor Strength | Hardwood, phenolic ply, reinforced steel sections; variable cross-bearer pitch | Matched to maximum forklift axle point loads (with FOS) and expected abrasion or impact exposure. |
| Aerodynamic Enhancements | Teardrop profiles, side skirts, diffusers, boat-tail | Specified for trunking routes or fuel-saving programmes; site clearance and operating speeds are key factors. |
Finance options
Finance can help operators align trailer investment with fleet replacement cycles or planned operational growth. Many fleets prefer structured payment schedules to support predictable budgeting and to introduce new equipment without significant upfront capital outlay.
Don-Bur works alongside established funding partners who understand commercial vehicle operations. This enables operators to explore lease or purchase arrangements that suit their own financial strategy and duty cycle.
FAQs
Do curtainsiders need to be EN 12642-XL rated?
EN 12642-XL is not legally mandatory, but it is widely specified because it provides recognised whole-body load containment performance. When loads are positioned to achieve positive fit, XL certification helps operators meet DVSA load-security expectations without relying solely on additional lashings for most palletised goods. All Don-Bur curtainsiders are built to EN 12642-XL as standard, providing a consistent and verified containment baseline across the fleet.
What does positive-fit loading mean?
Positive-fit loading means positioning freight so that it is held firmly against fixed structures with minimal free space. As a general guide, loads should be placed within 300 mm of the front bulkhead or rear closure and within 80 mm of the trailer sides, with no gaps between adjacent items within this zone. Maintaining positive fit reduces the potential for load movement during transport and is a key principle used in EN 12642-XL testing and DVSA load-security assessments.
How can I increase the durability of the curtains?
Curtains are wearable items, but longevity can be improved. Internal wear bands reduce abrasion from loads, top-mounted double rollers improve smooth sliding and reduce tension build-up, and UV-stable printed curtains retain colour for longer even with frequent cleaning. Ensuring that loads are positioned accurately and avoiding unnecessary contact with sharp edges also helps extend curtain life.
What load restraint systems are typically used in curtainsiders?
Common systems include EN 12195-2 compliant rave-to-rave webbing straps, transverse nets, side nets and EN 12640 lashing points. The correct method depends on load type and whether positive-fit loading can be achieved. These systems supplement, rather than replace, the containment provided by EN 12642-XL bodywork.
Which safety options are commonly specified?
Popular options include LowGlide, Leg-Safe, EBS-Safe, Direct Vision enhancements and vulnerable road user detection systems. These features support safer coupling, loading and urban operation while helping operators meet internal fleet safety policies and reducing the likelihood of avoidable incidents.
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